UN human rights boss Michelle Bachelet was given a mandate yesterday to collect and preserve information and evidence of crimes related to Sri Lanka's long civil war, which ended in 2009 with the defeat of the separatist Tamil Tigers.

The Human Rights Council adopted a resolution, brought by Britain on behalf of a group of countries, boosting her office's staff and powers, with a view to future prosecutions.

The vote at the 47-country forum in Geneva was 22 in favour, with 11 against including China and Pakistan, and 14 abstentions including India, the Phillipines and Japan. But Sri Lanka's ambassador, MCA Chandraprema, rejected the text as "unhelpful and divisive".

The resolution expressed serious concern at trends over the past year that represented "a clear early warning sign of a deteriorating situation of human rights".

These included putting military officers in charge of civilian government functions, an erosion of the independence of the judiciary, and impunity and "political obstruction of accountability" for crimes.

The UN believes 80,000 to 100,000 people died in the 26-year war, in which the Tamil Tigers hoped to carve out a separate state for the Tamil minority. In the final months, civilian deaths soared as the army pinned the Tigers into a tiny strip of the northeastern coast, where te UN says they kept hundreds of thousands of civilians as human shields.

In a report in January, Bachelet urged states to impose sanctions on former Sri Lankan military commanders.