Two women journalists of a Sri Lankan newspaper have received letters containing death threats, according to an international human rights organisation.

Two editors Frederica Jansz and Munza Mushataq of Sunday Leader in Sri Lanka, have received death threats by post, as hand-written letters in red ink, Amnesty International in a release said.

It is suspected that the letters are in connection with an article published by the newspaper on the infamous video that showed a Sri Lankan soldier allegedly shooting at point blank range a Tamil rebel who is bound and blindfolded.

The video also shows eight bound corpses, reinforcing allegations about summarily executions and extra judicial killings on part of the Sri Lankan troops.

Jansz, Editor-in-Chief and Mushataq is the News Editor of the newspaper both letters included text saying "if you write anymore, we will kill you, [and] slice you into pieces," according to Amnesty International.

The founder and former Editor-in-Chief of the newspaper, Lasantha Wickrematunge, was killed in January after receiving a similar death threat, the international human rights organisation has warned.

Meanwhile, the United Nations Special Rapporteur on arbitrary executions Philip Alston has said that he will initiate an inquiry into the incident.

"I have begun to commission some analysis of that video tape," Alston told journalists here.

He added he was doubtful that the Sri Lankan authorities could conduct fair and unbiased investigations. "I think that the track record shows very clearly that unless you have some real independence there the situation in Sri Lanka today is not one that will lend itself to an independent and impartial let alone convincing analysis," he said.