BEIJING: China on Wednesday banned exports to North Korea of technology and materials that might be used in weapons production in a new response to the North's development of nuclear weapons and missiles.

The list of banned "dual use" items with possible civilian and military use includes metal alloys, cutting and laser-welding equipment and materials that could be used in production of chemical weapons, the Commerce Ministry said.

Beijing has long supported the North Korean government but in a sign of growing frustration signed on in March to United Nations sanctions enacted in response to the North's fourth nuclear test. Those penalties include a ban on sales of "dual use" items.

North Korean leader Kim Jong Un's government has intensified nuclear activities in defiance of UN sanctions.

China is the impoverished North's main trading partner and aid donor, making its cooperation essential for the success of trade penalties.

In April, China banned imports of North Korean coal and iron ore, an important revenue source for the impoverished country. Beijing also banned sales of jet fuel to the North, though it said civilian aircraft would be allowed to refuel on flights to China.

Beijing balked at previous demands by Washington and other governments to use trade as leverage against North Korea. Chinese diplomats said the potential humanitarian impact of sanctions had to be considered.