The relationship between the United States and Pakistan is complicated and important, said White House spokesman Jay Carney on Wednesday.

He made the remarks after he refused to comment on reports that Pakistan has arrested some of the informants who tipped off the Central Intelligence Agency (CIA) on Osama bin Laden.

"I can say that our relationship with Pakistan is extremely important. It is also complicated. And we have made that clear and been quite candid about that for a long time," he said.

Carney said the relationship is important because it helps U.S. national security interest.

"Pakistan has worked with us to go after terrorism and terrorists. More terrorists have been killed on Pakistani soil than in any other country," he said.

He also refused to rank Pakistani cooperation on matters of counterterrorism on a scale of one to 10.

"Sometimes we have difficult issues to work through with them, but it remains an important relationship," he said.

A New York Times report said that Pakistan's intelligence agency has arrested some of the Pakistani informants who fed information to the CIA in the months leading up to the U.S. raid that resulted in the death of terror mastermind Osama bin Laden. Pakistan's military on Wednesday rejected such reports.