The United States has asked Pakistan to honour the diplomatic immunity to American citizen Raymond Davis, who was arrested for killing two people in Lahore, and release him under the Vienna Convention.

"We are concerned that the proceedings are ongoing," State Department spokesman P J Crowley told reporters after a Lahore court rejected Davis's claim for diplomatic immunity.

"We can't really comment on the litigation itself. We continue to stress to the Pakistani government and to the Pakistani courts that he has full immunity from criminal prosecution," he said.

The court indicated that in the absence of a certification by the government of Pakistan that Davis had diplomatic immunity, it would presume he did not have any such immunity.

"So that is not a definitive judgment. There is actually, later this month, a higher court hearing on the question of diplomatic immunity," he said.

Crowley insisted that the US had informed the government of Pakistan on the arrival of Davis in the country in January 2010 that he was attached to the administrative and technical staff of the US Embassy.

"And that was notification that he, in fact, has diplomatic immunity," he said. Pakistan, however, has refused to relent to US pressure to release Davis.