About 265,000 ethnic Tamils were displaced in the military's recent offensive against the Liberation Tigers of Tamil Eelam, or LTTE, and many of them have been sent to overcrowded camps in the country's north.
Under international pressure to reach out to the Tamil minority, Mahinda Rajapakse, Sri Lanka's president, vowed that a political solution to the country's ethnic divisions would be found.
"All should live with equal rights. They should live without any fear or doubt," he said in his victory speech on Tuesday.
"Let us all be united."
'Return and rebuild'
Rajapaksa called upon Sri Lankans, especially Tamils who fled the country, to return and help it rebuild.
"There are no minority communities in this country. There are only two communities, one that loves this country and another that does not," he said.
"We are a government that defeated terrorism at a time when others told us that it was not possible," Rajapakse said in a nationally televised address to parliament.
"The writ of the state now runs across every inch of our territory."
As he spoke, state television broadcast images of what it said was the body of Velupillai Prabhakaran, the LTTE chief.
The video showed the upper section of a corpse which was dressed in camouflage fatigues. The back of the head, which was resting on a bloodstained newspaper, appeared to be missing.
The face was intact, with the eyes wide open, and bore a clear resemblance to Prabhakaran.
Selvarasa Pathmanathan, the international spokesman for the LTTE, had earlier insisted that Prabhakaran was "alive and well".
The government's victory was overshadowed by what the United Nations said was the high cost of innocent lives.
The UN and human rights groups have partly blamed indiscriminate shelling by the military for causing heavy civilian casualties, while accusing the rebels of using tens of thousands of people as a
In New York, the Committee to Protect Journalists called for the release of three Sri Lankan doctors who treated wounded civilians in the country's war zone and were detained on accusations they gave false information about the number of casualties to the media.
"This is a chilling example of the intentions of the Sri Lanka government as it pursues its all out military solution in dealing with the [Tigers]," Bob Dietz, the groups Asia programme co-ordinator, said.
The European Union called for an independent inquiry into alleged human-rights violations, while the International Committee of the Red Cross complained it was unable to reach the wounded in the northeastern conflict zone even after victory was declared.
And Ban Ki-moon, the UN secretary-general, who is due to visit Sri Lanka at the end of the week, said in Geneva that any serious allegations of war crimes "should be properly investigated".
"I remain concerned about the welfare and safety of the civilian population," he said on Tuesday.
The UN's main rights body is to hold a special session on Sri Lanka next week.