As US intelligence agencies throw their weight behind the Indian investigation, President George Bush was being constantly kept informed about the investigation, White House spokeswoman Dana Perino said on Monday.
"I've heard nothing that says that the Pakistani government was involved," Perino told reporters, adding that President George W Bush "is currently in the situation room receiving an update on the recent attacks in Mumbai".
She said the American intelligence community is assessing all aspects of the terror attack and Washington had no reason to doubt Islamabad's assurance that it will provide complete cooperation into the investigation.
"We have no reason not to right now," she said, asked if the US trusted Pakistan to fully investigate the issue.
"The intelligence community is still assessing all spects of the attacks, the motivation, the plotting and lanning, and the operational details of it," she said on the Mumbai terror attacks that claimed close to 200 lives, including six Americans.
India has said Pakistan-based terror groups were involved into the attack, while Pakistan has denied any direct involvement.
On Secretary of State Condoleezza Rice's visit to India, Perino said the purpose is not only to show solidarity with New Delhi but also to stop the terror threat from expanding.
