U.S. President Barack Obama is pushing China to rein in North Korea's nuclear ambitions.

North Korea announced it'll launch a long-range missile next month, claiming it's in preparation for a satellite launch.

In a news conference in South Korea on Sunday, Obama said Beijing could use its influence over Pyongyang to stop the missile test Washington claims is part of a ballistic missile program.

(SOUNDBITE) (English) U.S. PRESIDENT BARACK OBAMA

"I believe that China is very sincere that it does not want to see North Korea with a nuclear weapon. But it is going to have to act on that interest in a sustained way."

He added that the launch would only further isolate North Korea, disrupt peace talks and derail a plan to resume much-needed food aid.

SOUNDBITE) (English) U.S. PRESIDENT BARACK OBAMA

"They need to understand that bad behaviour will not be rewarded. There has been a pattern for decades in which North Korea thought that if they act provocatively then somehow they would be bribed into ceasing and desisting acting provocatively."

The U.S. president is scheduled to meet Chinese President Hu Jintao on Monday.

Jessica Gray, Reuters