The founder of Pakistan's nuclear program claims that North Korea had paid top Pakistani military officials more than $3 million in exchange for nuclear technology in the 1990s.

Abdul Qadeer Khan released documents that detailed the secret transfer, including a North Korean official's 1998 letter to him, which was written in English.

The letter clearly says that more than $3.5 million and some jewelry was given to two Pakistani military officers for the delivery of missile components, a Washington Post report said on Thursday.

According to reports, western intelligence officials believe the letter is authentic, and that it contains details of sensitive matters known to few in Pakistan, North Korea and the United States. It also quoted a senior U.S. official as saying the information is consistent with prior knowledge of the same events.

However, Pakistani military officials named in the report deny the allegations, saying Khan wanted to shift the blame to others.

A Pakistani foreign ministry spokeswoman on Thursday also denied the report as totally baseless.

Khan who had spent five years under house arrest in Pakistan before being released in 2009 has also admitted to selling nuclear secrets to Libya, Iran and North Korea.

The documents were handed over by Khan to former British journalist, Simon Henderson, an expert on the Pakistani weapons program with the Washington Institute for Near East Policy -- who then provided them to The Washington Post.