BEIJING -- China has tightened restrictions on North Korea by issuing a long list of weapons-related technology and materials banned from export to its neighbour, reflecting Beijing's desire to get Pyongyang to scrap its nuclear programs and rejoin disarmament talks.

The announcement posted Tuesday on the Chinese Commerce Ministry website comes as two American experts said that Pyongyang can now make crucial equipment for producing uranium-based bombs on its own, cutting out imports that had been one of the few ways outsiders could monitor the country's secretive atomic work.

The list of forbidden items includes those with both civilian and military applications in the nuclear, ballistic, chemical and biological fields. The notice said the list was aimed at boosting enforcement of U.N. Security Council resolutions on North Korea passed since 2006.

The move is a continuation of China's new policy of putting slightly greater pressure on North Korea to coax it back to disarmament talks, said Li Mingjiang, China security expert at Singapore's Nanyang Technological University.

China could have simply implemented the ban, but announcing it so publicly was a sign to the U.S. and the rest of the international community that Beijing is sincere in meeting its commitments, Li said. He said it's also a rebuke to Pyongyang.

"The leaders in Pyongyang will hate this. They'll be angry," Li said. Pyongyang likely will "swallow the bitter pill" and may respond with concessions, he said.

Chinese Foreign Ministry spokesman Hong Lei declined to comment on the timing of the announcement, saying only that it "gives expression to the Chinese government's serious attitude to performing duties according to laws and regulations."

China, wary of undermining its isolated neighbour and creating instability on its northeastern border, has often argued against stricter sanctions on North Korea and has, at times, been accused of not enforcing them enthusiastically enough.

However, Beijing was angered by North Korea's long-range rocket launch last December and its third nuclear test in February, leading it to agree to tightened sanctions in March that also promise further measures in the event of another launch or nuclear test.

Since becoming North Korea's leader in December 2011, Kim Jong Un has repeatedly angered Beijing by refused to heed its prodding to engage in economic reform and return to nuclear talks.

U.S. officials have long pushed for tightened sanctions enforcement, with Secretary of State John Kerry, Under Secretary of Defence for Policy James Miller, and chief North Korea envoy Glyn Davies visiting Beijing on lobbying missions in recent months.

Those efforts have borne some success, with Chinese customs agents tightening inspections on a range of items, including luxury goods that Kim uses to shore up his support from the North Korean elite. In late 2011, Beijing forced the China Construction Bank to close accounts opened by the Korea Kwangson Banking Corp. and the Golden Triangle Bank to comply with previous U.N. sanctions.

China provides North Korea with a crucial economic lifeline, supplying almost all its fuel and more than 83 per cent of its imports, from heavy machinery to grain and consumer goods.

Ties between Beijing and Pyongyang had been seen to improve over the summer, but Chinese state media and government-backed scholars again criticized the North over its call last week for new talks without preconditions.

U.S. and other parties to the talks say they're not interested in sitting down with Pyongyang without clear signs it would honour a 2005 pledge to mothball its nuclear programs in return for aid.

Concerns over the North's nuclear program may rise following claims that Pyongyang is mastering domestic production of essential components for the gas centrifuges needed to make uranium-based nuclear bombs.

If Pyongyang can make crucial centrifuge parts at home, outsiders can't track sensitive imports. That could spell the end of policies based on export controls, sanctions and interdiction that have been the centerpiece of international efforts to stop North Korea's nuclear program over the last decade, Joshua Pollack, a Washington-based expert on nuclear proliferation, said in remarks prepared for delivery Wednesday at a Seoul symposium and provided in advance to The Associated Press.

"If they're not importing these goods in the first place, then we can't catch them in the act," said Pollack, who gathered the evidence with Scott Kemp, an expert on centrifuge technology at the Massachusetts Institute of Technology.

It's not clear whether North Korea has made bomb-grade uranium, and Pyongyang says the program is for peaceful, energy-generating purposes.

Earlier this year, during a barrage of threats aimed at Washington and Seoul, Pyongyang vowed to resume all its nuclear fuel production. Recent satellite imagery appears to show that North Korea was restarting its plutonium reactor.