The US will "investigate" Afghan President Hamid Karzai's allegation of involvement of Pakistan's ISI in the recent terrorist attack in his country, including the bombing of Indian embassy, President Bush has said.


"First of all, we'll investigate his charge and we'll work with his service...to get to the bottom of his allegation," Bush remarked on Karzai's statement.


Bush's statement came days after US Defence Secretary Robert Gates said there was no evidence available of Pakistan's involvement in the attack on Indian embassy in Kabul last week.


Bush said extremists were coming out of parts of Pakistan into Afghanistan which "should be troubling to Pakistan" as it was to Washington.


In a strongly worded statement on Monday, Karzai had said the attacks in Afghanistan were "carried out by the intelligence administration of Pakistan, its military intelligence institutions.