Washington, July 16: U. S. President George W. Bush has expressed his unhappiness over the movement of some extremists from Pakistan to Afghanistan.

Speaking at the White House, Bush said: "No question, however, that some extremists are coming out of parts of Pakistan into Afghanistan. And that''s troubling to us, it''s troubling to Afghanistan, and it should be troubling to Pakistan."

Bush said that the matter would be discussed with Pakistan Prime Minister Yousuf Raza Gilani here this month.

"As a matter of fact, we''ll have an opportunity to explore that further with Pakistan Prime Minister Yousuf Raza Gilani," he added.

Speaking on involvement of elements of the Pakistani intelligence services in attacks in Afghanistan, he said, "The US will investigate charges made by Afghan President Hamid Karzai. We will work with his service to get to the bottom of his allegation."

"Pakistan is an ally. Pakistan is a friend. And I repeat, all three countries, the United States, Pakistan and Afghanistan, share a common enemy," the News quoted Bush as saying.

Terming wars in Afghanistan and Iraq as the "big challenge of the time", Bush said, "We''re committed". (ANI)