Military officials initially thought the blast had been caused by a grenade attack, but later tracked it down to the three-wheeler.
Kumaratunga told visiting European Union Commissioner for External Relations Benita Ferrero-Waldner Monday that she expected talks to begin soon for lasting negotiated settlement in the country.
The Lankan president threatened serious action if the LTTE does not stop the killings.
The powerful bomb blast is believed to be triggered by a suicide bomber.
Diplomats expressed fears that the rebel Liberation Tigers of Tamil Eelam could resort to more guerrilla attacks in the coming weeks as the peace process ground to a halt.
Sri Lanka rules out Oslo, Norway as venue for truce talks with LTTE.
the Navy exchanged fire with a flotilla of Liberation Tigers of Tamil Eelam after the rebels attacked naval gunboats.
Sri Lankan navy seize explosives, detonators in Jaffna
Rejecting reports of fresh talks, the LTTE said it would resume talks only on the basis of their "Interim Self-Governing Authority" plan unveiled in October last year.
The army attributed the killings to factional fighting within the LTTE.
Officials said they suspected Tiger rebels were behind the killing. The base their suspicions on the fact that Tiger rebels had accused the military intelligence of supporting a breakaway rebel faction.
The defence ministry said the students carried the grenade, which exploded accidentally and caused their deaths.\n
As many as 18 soldiers were killed in Puloly in two similar attacks early in December.
They are our closest neighbour and it is very important for me to have them involved in the process, said Rajapakse.
Japan's special peace envoy to Sri Lanka Yasushi Akashi offered to host the talks after the government said it was no longer insisting negotiations must be held within the island
Rajapakse says he is ready to talk to Tigers
'There is no clarity in the government's offer,' the LTTE said. 'It does not specifically address the concerns raised by the Tigers.'
It was not immediately clear how he would celebrate his birthday, but he is expected to deliver his annual "heroes' day" address Saturday setting out the policy direction of his movement.
Chandrika Kumaratunga did not say what action her government would take if the Tigers did not respond to her two-week deadline.
The "message" was given to Norwegian Foreign Minister Jan Petersen during his meeting with LTTE chief Velupillai Prabhakaran.
The Liberation Tigers of Tamil Eelam said it was not bound by a declaration issued by international donors who pledged some $4.5 billion to help rebuild Sri Lanka at a June 2003 meeting in Tokyo.
"We will leave the government if the President does not withdraw the joint mechanism plan with Liberation Tigers of Tamil Eelam by June 15," the Marxist Janatha Vimukthi Peramuna or People's Liberation Front said.
The government claims that the tigers have two aircraft.
Manoj Bajpayee simply lives, and loves, the role -- of a man who life is fast passing by, and who continues to live the lie of a simple government servant, observes Saisuresh Sivaswamy.
Marumalarchi Dravida Munnetra Kazhagam leader Vaiko had demanded the lifting of the ban on the Liberation Tigers of Tamil Eelam.
The UNICEF spokesman said the agency had hoped that the gravity of the unprecedented calamity would see a stop to the LTTE's child recruitment.
The principal of a government polytechnic in Kerala and four students were among seven people booked by police on Tuesday over putting a photograph of Prime Minister Narendra Modi in their campus magazine under a list of 'negative faces' that also included Adolf Hitler, George W Bush and Osama bin Laden.
'Suspect all, fix all.' 'It is this mindset that begins at the very top of an establishment and then trickles down and across,' notes Shekhar Gupta.
Though dubbed as the 'war hero', the role of Rajapaksa in ending the conflict with the LTTE with the death of its supremo Velupillai Prabhakaran in 2009 is quite divisive as he stands accused of violating human rights, a charge he vehemently denies.
The National Tawheed Jamath is suspected of plotting the deadly Easter blasts.
Sri Lanka's new President Maithripala Sirisena on Monday unveiled his cabinet that included members from a cross-section of parties and announced fresh parliamentary polls in 100 days, two years ahead of schedule.
'Outsiders are the ones who have to make the biggest journey to realise themselves, to come back to some sense of normality.' Director Jacques Audiard and actor Jesuthasan Antonythasan discuss the human landscape behind the award-winning film, Dheepan, with Aseem Chhabra/Rediff.com
Intelligence Bureau officers say the problem lies with the government treating narcotics and terrorism as two separate problems, with different law-enforcing agencies for each, and this ends up in defeating the purpose. Vicky Nanjappa reports.
Skeletal remains of 80 bodies have been dug out of a mass grave in a former Liberation Tigers of Tamil Eelam stronghold in Sri Lanka, fuelling speculation that the bodies are of Tamil civilians who disappeared during the war with the rebels.
Maithripala Sirisena, Sri Lanka's president-elect, was a low-profile cabinet colleague of longtime president Mahinda Rajapaksa until he switched sides to become joint opposition candidate and emerge as the proverbial dark horse in the presidential polls.
Cassandras and Congressis may sneer at the findings, but the Times Now poll indicated that the Modi government was very much on its way to a second term.
Voters in Sri Lanka's Tamil majority Northern Province on Saturday began voting in the first local elections in 25 years to elect a council to govern the former war zone, four years after the military defeated the Liberation Tigers of Tamil Eelam after decades of bloody civil war.