Heavy rains have forced the government to postpone indefinitely a parade planned for Thursday to commemorate its declaration of victory on 18 May 2009.
"The government has decided to postpone the war heroes' commemoration ceremony which was due to be held at the War Heroes' Monument at the parliament grounds," the defence ministry said in a statement on Tuesday.
Meanwhile, a report by the Brussels-based International Crisis Group (ICG) slams the government for human rights violations during the war.
And the ICG accuses the UN and the “international community” of ignoring civilian suffering so as to maintain good relations with Colombo.
"The UN needs to examine its behaviour in the last few months of the war, when it was often more concerned about maintaining its ability to work with the Sri Lankan government than it was for standing up for the values that the UN represents,” says the ICG's Asia Programme Director Robert Templer.
“And this is particularly true in the case of conflict areas where it should side with the important rule of not allowing civilians to be slaughtered. We do feel the UN fell down as an institution in many of these areas."
The UN estimates that about 7,000 civilians were killed during the offensive and has called for an investigation.
The ICG says that during the conflict the UN “too readily complied with the government’s demands to withdraw from conflict areas”.
The ICG also accuses foreign powers of going along with violations of international law because they “welcomed the LTTE’s defeat, regardless of the cost of immense civilian suffering and an acute challenge to the laws of war”.
The government herded 300,000 Tamil civilians into camps towards the end of the war, while there were numerous accusations of troops firing on civilians or preventing them from leaving war-hit areas.
"The evidence that we have shows that there was a deliberate effort to target humanitarian action and hospitals by the Sri Lankan military, and those constitute war crimes under the Rome statute," Templer told RFI.
"We also found that the number of deaths was significantly higher than figures released either by the Sri Lankan government or by the United Nations."
"We also looked at war crimes by the LTTE and found significant abuses of the civilian population by the Tamil Tigers."
General Sarath Fonseka who led the operation against the Liberation Tigers of Tamil Eelam (LTTE) is in a naval detention cell, awaiting court martial after unsuccessfully challenging president Mahinda Rajapakse in this year’s election.
A new organisation set up by Tamils living abroad, the Global Tamil Forum, is observing Tuesday across the world as a day of remembrance of Tiger fighters and civilians killed in the final phase of fighting.
The Sri Lankan government accuses the forum of being an LTTE front expressed fears that Tiger remnants would try to regroup and rearm with the support of Tamils living abroad.