By Megha Rajagopalan

BEIJING (Reuters) - China called on Saturday for all parties involved in talks on North Korea's nuclear program to adopt a responsible attitude and not take any action to exacerbate tension, as it pushed again for a resumption of the stalled negotiations.

This week, the North announced a plan to fire a long-range rocket that it says is for a space program. It also said it was working to improve its nuclear arsenal.

North Korea is expected to launch an upgraded long-range ballistic missile, which would violate international sanctions, as it prepares to celebrate the anniversary of the founding of its ruling Workers' Party of Korea on Oct. 10.

Any such launch would violate international sanctions.

"We call on all sides to adopt a responsible attitude toward the peninsula as well as the region of northeast Asia, and never again take any new action that could lead to tensions in the situation there," Chinese Foreign Minister Wang Yi told an academic forum on the North Korea talks issue, without directly mentioning any country.

While China has been angered by North Korea's provocative behavior, it has also been critical of military exercises staged by South Korea and the United States for exacerbating tension.

South Korea has been restrained in its response to the North's latest tough talk though, a sign it does not want to disrupt a fragile improvement in ties after negotiations ended a tense standoff last month.

"If there is war or chaos on the peninsula, it benefits no one," Wang added. "If denuclearization issue is not resolved, there is no way the peninsula will be stable, and it will be difficult for northeast Asia to be at peace."

In 2005, North Korea reached an agreement with the United States, South Korea, China, Japan and Russia to suspend its nuclear program in return for diplomatic rewards and energy assistance.

Numerous efforts to restart the talks have failed after negotiations collapsed following the last round in 2008. At the time, North Korea declared the deal void, after refusing inspections to verify compliance.

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North Korea has called for the resumption of the talks, but the United States and South Korea have said it must first show it is serious about ending its nuclear program.

Ties between North Korea and its most important ally, China, have also cooled since Kim Jong Un assumed power in Pyongyang and, in 2013, carried out a third nuclear test, in defiance of U.N. sanctions.

(Writing by Ben Blanchard; Editing by Robert Birsel)