BEIJING (REUTERS) - China's Foreign Ministry pushed back against US pressure on North Korea and the disputed South China Sea on Friday, as US Secretary of State John Kerry arrived in Beijing for high-level meetings.

Speaking in Seoul before leaving for Beijing, Mr Kerry said China should be doing more to help nudge Pyongyang - which has rattled the region with nuclear tests and angry rhetoric - into line.

Asked about that remark, Chinese Foreign Ministry spokeswoman Hua Chunying said China had been working hard to get North Korea to return to talks on its nuclear programme, pointing out Chinese diplomats visited Pyongyang recently.

"China as a responsible, big country has been actively promoting and resolving the nuclear issue and has played its due role," Ms Hua told a daily news briefing.

"We have, through different channels, worked on the North Korea nuclear problem through the six-party nuclear talks, and have maintained close communication with the parties."

North Korea was raised during Mr Kerry's meeting with Chinese President Xi Jinping, according to the official Xinhua news agency, with Mr Xi "setting forth China's stance". The report provided no other details.

The East and South China Seas are likely to feature prominently on Mr Kerry's agenda too.

The United States has been increasingly uneasy at what it sees as China's effort to gain creeping control over waters in the Asia-Pacific region, including its Nov 23 declaration of an air defence identification zone (ADIZ) in an area of the East China Sea that includes islands at the centre of a dispute with Japan.

China also claims about 90 per cent of the 3.5 million square km South China Sea, depicting what it sees as its area on maps with a so-called nine-dash line, looping far out over the sea from south China.

On Thursday, the commander of the US Navy said the United States would come to the aid of the Philippines in the event of conflict with China over disputed waters in the South China Sea.

Ms Hua said the United States should stick to its promises and not take sides in this dispute.

"The United States is not a party in the South China Sea dispute, and should... be careful in its words and actions, and do more that will benefit true peace and stability in the region rather than the opposite," she said.