North Korea's leader Kim Jong Il says ties with China are "unbreakable" and has called for increased cooperation between the communist nations amid international pressure on Pyongyang to return to nuclear disarmament talks.

Kim made the comments during a meeting Wednesday in the North Korean capital with Chinese Defense Minister Liang Guanglie, China's official Xinhua News Agency said.

Liang is the latest high-level Chinese official to visit North Korea as the two communist nations mark 60 years of cooperation. China, which backed North Korea during the 1950-53 Korean War, is its main source of economic aid and diplomatic support.

Kim called their friendship "a treasure inherited from the older generations," and said it "had stood the test of history and was unbreakable," according to Xinhua.

He said the two sides should continue to "boost exchange and cooperation."

Liang said the Chinese government was "unshakable" in its commitment to develop cooperation between the two nations.

Liang's visit comes amid renewed efforts to draw North Korea back to international negotiations on dismantling the regime's nuclear program.

North Korea, which conducted an underground nuclear test, and test-fired a series of missiles in May, abandoned the talks earlier this year.

President Barack Obama announced in Seoul last week that he would send a special envoy to Pyongyang on Dec. 8 to discuss restarting the six-nation talks hosted by China and also involving Japan, South Korea and Russia.

Kim has said Pyongyang may consider rejoining the talks depending on the outcome of direct talks with the United States.