Human rights activists in Sri Lanka have blamed the government for the deaths of Tamil detainees after violence in a Vavuniya prison and called for an UN-led investigation the deaths, reported the BBC on Wednesday.

A total of 28 activists have issued a statement, saying the deaths of Nimalaroopan and Dilrukshan were caused by torture, inflicted by prison officers, after detainees protested over the disappearance of a fellow Tamil inmate.

"We, the civil society, have lost confidence in domestic mechanisms in being able to deal with such situations," they write.

They have called on the government to appoint an inquiry, which will be controlled by the UN's Office of the High Commissioner for Human Rights, Navi Pillay.

Charles Haviland, the Sri Lanka correspondent for the BBC, highlighted the protests in Jaffna by Tamil activists against the killings and drew attention to the difference in media coverage on the island.

"Media coverage of the episodes has highlighted Sri Lanka's ethnic faultlines." he wrote.

"Sinhala-language media have tended to describe the prisoners as 'terrorists', while Tamil-language outlets have termed them 'political prisoners'."