North Korea would possess some 20 nuclear bombs by 2016, and it could conduct several rounds of detonation tests to miniaturize nuclear warheads, a renowned U.S. nuclear scientist said Wednesday.

"North Korea is presumed to have the capability of producing some four nuclear bombs per year, and it appears that the North will possess some 20 nuclear bombs by 2016," Siegfried Hecker, a research professor at Stanford University who visited the North's Yongbyon nuclear complex in 2010, was quoted as saying by Rep. Yoo Ki-june of South Korea's ruling Saenuri Party.

In April, Hecker estimated that North Korea had about 10 nuclear bombs, according to sources in Washington.

The expert, who came to Seoul to participate in the 13th Korea-U.S. West Coast Strategic Forum on Thursday, made the remarks during a Wednesday meeting with a group of lawmakers of Seoul's parliamentary Foreign Affairs and Unification Committee. Yoo is the head of the committee.

Speaking of the communist country's attempts to miniaturize a nuclear warhead for missiles, Hecker raised the chances of Pyongyang's further underground tests.

"For the miniaturization, the North could carry out several rounds of nuclear tests down the road," Hecker was quoted as saying. "North Korea appears not to be sure (about the technology)."

Pyongyang has conducted three nuclear tests since 2006, including its most powerful one with a uranium-based device in February 2013. The bellicose state has threatened to carry out "a new form" of underground test.

Though the North has yet to demonstrate the miniaturization capability, officials and experts from South Korea and the U.S. have said the communist country is believed to have the technology to build nuclear-tipped missiles. (Yonhap)