Relatives of those killed have still not received justice
A human rights group in Sri Lanka has blamed local security forces for the massacre of 17 aid workers in 2006 and accused the government of a cover-up.
The bodies of the Action Against Hunger workers were found in the north-eastern town of Muttur.
It was one of the worst attacks on humanitarian workers since the 2003 bombing of the UN compound in Baghdad.
The government has responded by saying that the killing of the workers is now the subject of a commission of inquiry.
"The public can share information in relation to this incident with the commission and if it is helpful this will be used when it formulates its conclusions," Minister for Human Rights Mahinda Samarasinghe told the BBC Sinhala service.
The University Teachers for Human Rights (UTHR) has named three people - a local home guard and two police constables as the killers of most of the 17 local aid workers in August 2006.
"The evidence shows state security forces, including police, killed them and that senior police officers covered it up," said UTHR spokesman Rajan Hoole.
The aid workers' bodies were exhumed
"The killing of civilians during time of conflict is a war crime. The perpetrators and their superiors should be brought to justice."
The mainly ethnic Tamil workers were involved in rebuilding the north-east of Sri Lanka two years after the 2004 tsunami.
They were found lying face down with bullet marks in their heads in an Action Against Hunger compound in the predominantly Muslim town of Muttur.
The military said they were trapped in fighting between troops and rebels. It has blamed the Tamil Tigers for the murders.
The report said the brother of the home guard had been killed by a Tiger gunman the previous day and he wanted vengeance.
It said that there was a culture of impunity in Sri Lanka as the 2002 ceasefire collapsed into open war.
UTHR said publishing the report was risky, because three witnesses had already been killed, a fourth had gone missing and others had fled the country.
Meanwhile an international panel invited by Sri Lanka to observe the government's probe into human rights abuses has shut down, three weeks after accusing Colombo of failing to tackle the issue.
The International Independent Group of Eminent Persons (IIGEP) was formed to observe an inquiry into 16 cases of serious rights violations, including the August 2006 massacre.
In a statement on Monday, the IIGEP said they were halting their efforts to determine whether the inquiries were being conducted "in accordance with internationally accepted norms and standards".
Earlier this month, the group had accused the government of lacking the political will to investigate the incidents and said Sri Lankan authorities did not meet the basic minimum standards in investigating serious rights abuses.
The IIGEP's final report is expected to be presented to Sri Lankan President Mahinda Rajapakse next month and the panel's office will formally close on 30 April, the statement said.
Mr Samarasinghe said that while the withdrawal was "regrettable", he was confident that the inquiry into the Muttur killings - and another inquiry into the 2006 killing of five students in the eastern town of Trincomalee - would meet international standards.