North Korea asked China last month to be recognized as a nuclear weapons state, a source familiar with Seoul-Beijing affairs said Sunday, amid indications China is taking a firm stance against Pyongyang's nuclear weapons programs.

North Korean Vice Marshal Choe Ryong-hae made the request in a meeting with Chinese President Xi Jinping during his visit to Beijing last month, according to the source inside South Korea's ruling Saenuri Party.

"The Chinese side expressed its negative stance on North Korea's request," the source said, speaking on condition of anonymity.

Choe visited Beijing as a special envoy of North Korean leader Kim Jong-un, raising the possibility that he made the request at Kim's instructions.

The source said a high-ranking Chinese military official told a team of South Korean civilian and military representatives about Choe's request during its recent visit to China.

Beijing, Pyongyang's main ally and benefactor, has recently shown signs that it is taking a firm stance against its communist neighbor's nuclear weapons programs.

Earlier this month, Xi and U.S. President Barack Obama agreed that they will not recognize North Korea as a nuclear weapons state or accept its development of nuclear weapons.

The issue of North Korea's nuclear weapons is expected to be a key topic during South Korean President Park Geun-hye's upcoming summit with Xi in Beijing later this month. (Yonhap News)