Sri Lanka Thursday published a roadmap for investigating allegations that elements of the military were responsible for civilian deaths during its final battle with Tamil Tiger rebels in 2009.

The plan, which sets timetables for probing the charges and punishing those found guilty of excesses, follows EU and US pressure for Colombo to implement recommendations of a national commission that studied the last stages of the Tamil conflict.

In its report made public last December, the government-appointed Lessons Learnt and Reconciliation Commission (LLRC) had noted "considerable civilian casualties" and the fact that army shells had fallen on civilian hospitals.

While concluding there was no military policy of deliberately targeting civilians, the commission urged the government to investigate certain incidents that might point to "wrongful conduct".

The roadmap published Thursday commits the security forces to complete ongoing "disciplinary" investigations within 12 months and ensure that any resulting criminal charges are filed in court within another four years.

It also gives the army six months to complete "follow up action" over allegations contained in a British television documentary that members of security forces had killed scores of surrendering Tamil rebels in 2009.

The alleged disappearances of thousands of people during the fighting would also be investigated, the government said in a statement.

"We take the LLRC recommendations very seriously and we hope to be able to implement most of these recommendations within three years," said Lalith Weeratunga, the top civil servant in the country.

Human rights groups have said up to 40,000 civilians perished in the final months of the military campaign against the Tamil Tiger rebels.