Washington: The United States is not able to confirm a claim by al Qaeda in the Indian Subcontinent (AQIS) that the group killed a blogger Avijit Roy who was also a US citizen in Bangladesh in February, a US official said on Monday.

The SITE Intelligence Group reported on Sunday that AQIS leader Asim Umar claimed responsibility for the killing of Avijit Roy, a US citizen of Bangladeshi origin, in a video listing several people killed in Bangladesh and Pakistan. \

‘We are aware of the 2 May claim of responsibility for the murder of the American-Bangladeshi blogger Avijit Roy by AQIS,’ an official of the US State Department said. ‘However we cannot independently confirm who is responsible for this despicable act of terrorist violence.’

On Sunday, Bangladeshi police stood by their assessment that Avijit's murder was the work of a local militant group called the Ansarullah Bangla Team, which claimed responsibility shortly after the attack. They said they would now have to investigate whether it was working as a branch of al Qaeda.

The US official said the United States had provided support to Bangladesh during the initial stage of the investigation into Avijit's killing.

Avijit, who wrote a blog that highlighted humanist and rationalist ideas and condemned religious extremism, was hacked to death by machete-wielding assailants in Dhaka on 26 February. His family said radical Islamists were to blame.

SITE, which monitors Internet messages posted by jihadist groups, said AQIS leader Asim Umar made his claim in a nine-minute video, listing several people killed in Bangladesh and Pakistan.