As government forces tighten their grip on a narrow spit of land in northeastern Sri Lanka and the last remants of the Liberation Tigers of Tamil Eelam (LTTE), who have been fighting for an independent Tamil homeland since 1983, international concern over the safety of thousands of civilians trapped alongside them intensifies.
More than 100,000 civilians have fled the combat areas since 20 April, while the UN estimates that up to 50,000 non-combatants remain trapped inside.
IRIN takes a look back at one of the Asia's bloodiest conflicts, which has resulted in more than 70,000 people killed and thousands more displaced over more than two decades.
A chronology of key events
1972: Velupillai Prabhakaran forms a militant group called the Tamil New Tigers (TNT).
1976: TNT changes its name to the Liberation Tigers of Tamil Eelam (LTTE).
1983, 23 July: LTTE attacks an army patrol in Jaffna, killing 13 soldiers and sparking anti-Tamil riots around the country, leaving several hundred dead.
1985, 8 July: Talks held between the Sri Lankan government and the LTTE for the first time in Thimpu, Bhutan.
1987, 29 July: Indo-Sri Lanka pact signed between President JR Jayawardena and Prime Minister of India Rajiv Gandhi. India deploys peace-keeping force to north and east Sri Lanka.
1990, 24 March: India withdraws troops due to clashes with the LTTE killing more than 1,200 Indian troops.
1990 June: LTTE kills hundreds of policemen in the east following breakdown of talks between the Tigers and the government of President Ranasinghe Premadasa.
1991, 21 May: Gandhi killed, allegedly by an LTTE suicide bomber.
1993, 1 May: Premadasa killed by LTTE suicide cadres during a May Day rally in Colombo.
1995, January: Government of Chandrika Kumaratunge and LTTE agree to talks.
1995, April: Talks fail after the Tigers blow up two navy vessels.
1995, 2 December: Jaffna, the northern cultural and political nerve centre of the Tamils, falls under Sri Lanka army control.
1996, 31 January: Suicide bomb attack on the Central Bank building in the heart of Colombo kills more than 100 and injures 1,400.
1996, 24 July: Alleged LTTE bomb blast in a railway station in Dehiwela, south of Colombo, kills 70.
1996, 18 July: Army camp overrun by the LTTE near the northeastern town of Mullaitivu. More than 1,000 troops killed.
1998, 25 January: Suicide bomb attack on Sri Lanka's holiest Buddhist shrine, Dhaladha Maligawa (Temple of the Tooth), in the central town of Kandy, kills 17 people.
1998, 26 September: Tigers overrun Kilinochchi army camp, killing more than 1,000 government soldiers.
1999, December: LTTE attempts to assassinate President Chandrika Bandaranaike Kumaratunge; he survives.
The ICRC and the Sri Lanka government have used ferries to transport injured civilians and their dependents out of the combat zones to Trincomalee port. They have also used the ferries to deliver food, medicine and other essentials to endangered civilians
Photo: Sri Lanka Ministry of Defence
The ICRC and government have used ferries to transport injured civilians and their dependents out of the combat zones
2000, April: LTTE recaptures Elephant Pass, inflicting heavy damage on the Sri Lankan forces during the operation Unceasing Waves III.
2001, July: An LTTE suicide attack on Bandaranaike International airport kills 14.
2002, 22 February: Ceasefire agreement, brokered by Norway, signed by Prime Minister Ranil Wickremesinghe and LTTE leader Prabhakaran.
2002, December: Government and LTTE agree to share power at peace talks in Norway.
2003 April: LTTE pulls out of talks after six rounds of negotiations, citing inadequate steps taken to rebuild war-hit areas.
2004, 3 March: LTTE eastern military head, Vinayagamurthi Muralitharan, alias Karuna Amman, splits from the LTTE.
2005, 7 February: LTTE political head for the eastern Districts of Batticaloa and Ampara, E. Kousalyan, killed with three others in Batticaloa town.
2005, 12 August: Foreign Minister Lakshman Kadirgamar killed by suspected LTTE snipers in Colombo.
2005, 4 December: The LTTE commences claymore and grenade attacks targeting the Sri Lankan troops in the Jaffna peninsula.
2006, 15 June: More than 60 civilians killed in claymore mine attack allegedly by LTTE, targeting a civilian bus in Kebithigollewa, nearly 200km from Colombo.
2006, 20 July: LTTE closes the sluice gates at Mavilaru, south of the eastern coastal town of Trincomalee. Clashes erupt as army launches operations to gain control and succeeds.
2007, 5 January: Bomb attacks on public transport begin in Nittambuwa, about 20km east of Colombo, killing six people. Several bombs target public transport in the following months. The government blames the LTTE for the attacks.
2007, March: LTTE carries out its first air raid on Katunayake air base, about 20km north of Colombo. The Tigers also conduct an air attack on 29 April during the Cricket World Cup Final. The attack targets two fuel-storage facilities on the outskirts of Colombo. The Tigers carry out at least nine air attacks before 20 February 2009.
2007, 15 January: Military captures Vakarai, a coastal town in Batticaloa District in the Eastern province.
2007, 11 July: military captures Thoppigala, the last of the LTTE strongholds in the east after 13 years, thereby regaining the entire eastern province from the LTTE.
2007, 2 November: LTTE political wing leader SP Tamilselvan killed in an air raid by the Sri Lankan Air Force.
2008, 2 January: The government says it will withdraw from ceasefire agreement and does so on 14 January and intensifies attacks on the Tigers. The LTTE, however, states it will stick to the agreement.
2008, September: All international humanitarian agencies and their foreign staff operating in the LTTE-controlled Kilinochchi and Mullaitivu districts are ordered by the government to relocate to Vavuniya.
2009, 2 January: Government troops capture Kilinochchi, de-facto capital of the LTTE, after 10 years.
2009, 25 January: Mullaithivu town captured by government troops.
2009, 12 February: Government declares a 12km-long "no fire zone" (NFZ) along the Mullaitivu western coast and calls on civilians to move into it for their own safety.
2009, 20 February: The LTTE conducts a suicide air attack in Colombo.
2008 March: Sri Lankan troops launch operations to regain areas in the Vanni from the western flank. The number of civilians in the NFZ continues to grow.
2009, 14 April: LTTE says it is ready for negotiations, but the government refuses the offer, insisting it should lay down arms.
2009, 20 April: Thousands of civilians trapped in the NFZ cross into government-controlled areas where they are screened and placed in camps. Government gives LTTE 24 hours to surrender.
UN Humanitarian Chief John Holmes urged combatants to ensure the safety of civilians trapped inside the combat zone at the end of a three day visit to Sri Lanka
Photo: Amantha Perera/IRIN
John Holmes, the UN humanitarian chief, in late April urged combatants to ensure the safety of civilians trapped inside the combat zone
2009, 22 April: Former LTTE media coordinator Velayutham Dayanidhi, alias Daya Master, and the translator of former LTTE political wing head SP Tamilselvan, Kumar Pancharathnam, alias George, surrender to the military.
2009, 26 April: The LTTE declares a unilateral ceasefire as government forces surround an ever-shrinking NFZ. The government rejects the declaration, calling it a "joke". The UN estimates 50,000 civilians remain trapped in the NFZ.
2009, 27 April: Facing with diplomatic pressure to declare a ceasefire, Sri Lanka says its military is no longer using heavy weaponry and aerial bombing against the remaining few hundred rebels still fighting in the NFZ.
2009, 28 April: With more than 150,000 internally displaced persons (IDPs) in camps in Vavuniya, Jaffna, Mannar and Trincomalee, UN Emergency Relief Coordinator John Holmes urges that civilians who have been screened be given the chance to leave the camps and to rely on friends and family elsewhere.
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This article was produced by IRIN News while it was part of the United Nations Office for the Coordination of Humanitarian Affairs. Please send queries on copyright or liability to the UN. For more information: https://shop.un.org/rights-permissions