White House Press Secretary Jay Carney says the United States takes North Korea’s nuclear program “very seriously.”

Carney made the comment during a news briefing on Thursday after being asked whether the U.S. has any evidence that North Korea has been bribing Pakistan to get nuclear technology.

The press secretary's briefing follows a Washington Post report that the North paid off top military officials in Pakistan to obtain access to sensitive nuclear technology in the late 1990s.

The report said Abdul Qadeer Khan, the founder of Pakistan's nuclear industry, presented documents that he said support his claim that he personally transferred more than three million dollars in bribe money from North Korea to senior officers in the Pakistani military.

The daily added that Khan also released what he says is a copy of a 1998 letter in English from North Korean Workers’ Party Secretary Jon Byon-ho that spells out details of the secret deal.