British Premier David Cameron and other Commonwealth leaders going to the summit in Sri Lanka this week “have a duty to hold their hosts to account” for crimes against humanity there during and since the war’s end, The Times newspaper said in its editorial Tuesday.

By allowing Sri Lanka to host its heads of government meeting in Colombo, the Commonwealth risks “collud[ing] with crime and cover-up on an historic scale,” the paper said.

“The evidence of crimes against humanity by [Sri Lankan] troops during and since the climax of the Sri Lankan civil war, collected mainly by British journalists, is appalling and authentic beyond reasonable doubt.”

Mr. Cameron “must be ready to use the full weight of his office and the Commonwealth to demand the independent investigation that [President] Rajapaksa has refused. Anything less would make the Commonwealth complicit.”

“The diplomatic set pieces of a summit unavoidably carry a message of endorsement for its host. Mahinda Rajapaksa, Sri Lanka’s President, craves such endorsement, but he does not deserve it. [And] as he prepares to receive [Commonwealth] delegations, Mr Rajapaksa should not delude himself that his efforts to suppress the truth about his human rights record have triumphed,” the paper said.

Along with the boycotts by the leaders of Canada and India, the paper said “Britain has sent a signal, too: this will be the first such summit not attended by the Queen since 1971.”