"He (Rajapaksa) was publicly lamenting that he was to be taken before a war crimes court and executed on an electric chair. The people who voted me against him have prevented that," Sirisena said, responding to Rajapaksa's statement on the UN human rights chief's visit to the country.
Sirisena said his victory in elections in January last year over Rajapaksa was the reason why the former President was prevented from answering a war crimes probe.
"There was an attempt to portray this UNHRC resolution as a great diplomatic victory for Sri Lanka. But in reality, it was a great betrayal," he had said.
UN human rights chief visited the country to review the measures taken by the island-nation to investigate alleged atrocities committed during the long civil war that left tens of thousands dead.
According to UN figures, up to 100,000 people were killed in the three-decade long civil war. Hundreds of people are still missing.
In the hard-hitting report submitted by him at the UNHRC last September, Hussein had criticised Sri Lanka's failure to deliver justice to the victims of the 26-year conflict.
He has prescribed an international "hybrid court" with foreign judges, prosecutors and investigators. to Sri Lanka.
The UNHRC resolution co-sponsored by Sri Lanka has mandated an accountability probe focussed both on the government troops and the LTTE.
Sirisena government has adopted a conciliatory attitude towards the UNHRC.
