The United States and China must find a way forward on reining in North Korea's nuclear programme and easing tension in the South China Sea, U.S. Secretary of State John Kerry said on Wednesday during a meeting with Chinese Foreign Minister Wang Yi.

Kerry, on a two-day visit to Beijing, had been expected to press China to push for more curbs on North Korea after it said it had successfully conducted a test of a miniaturized hydrogen nuclear device on Jan. 6.

Beijing, Pyongyang's lone major backer, has criticized remarks by State Department officials urging China to do more as irresponsible, saying it has made great efforts to achieve de-nuclearization on the Korean peninsula.

Though the United States and China had made good progress on issues from climate change to counter-terrorism, "clearly we have several important issues that we need to find the way forward on," Kerry told Wang, according to a pool report on the meeting.

"One is the nuclear programme of the DPRK, North Korea, a major challenge to global security, one of the most important issues for the security of the United States of America," Kerry said, referring to North Korea by its official name, the Democratic People's Republic of Korea.

The 15-member UN Security Council said at the time of North Korea's test that it would begin working on significant new measures in response, a threat diplomats said could mean an expansion of sanctions.

Since then, diplomats said Washington and Beijing have been primarily negotiating on a draft resolution, but when asked on Saturday if they were nearing agreement, U.S. Ambassador to the United Nations Samantha Power said no.

China seems to downplay its influence

In a sign that Beijing could be reluctant to take a more hardline stance on North Korea, state news agency Xinhua said it was "unrealistic to rely merely on China to press the DPRK to abandon its nuclear programme, as long as the U.S. continues an antagonistic approach wrought from a Cold War mentality."

"Bear in mind that China-DPRK ties should not be understood as a top-down relationship where the latter follows every bit of advice offered by the former," Xinhua said.

Xinhua commentaries are not official government pronouncements, but can be read as a reflection of official thinking.

Kerry also told Wang that the two countries had to make progress on "concerns and activities in the South China Sea." China claims almost all the disputed waters in the potentially oil- and gas-rich South China Sea, parts of which are also claimed by Brunei, Malaysia, the Philippines, Taiwan and Vietnam.

It has been building up facilities on islands it controls, angering the Philippines and Vietnam and drawing criticism from the United States, which has expressed deep concern that the construction will exacerbate tension in the region.

Kerry was in Cambodia on Tuesday after a visit to neighbouring Laos as part of an effort to urge unity among leaders of the 10-nation Association of Southeast Asian Nations (ASEAN), before a summit with President Barack Obama in Sunnylands, Calif., next month.

China insists any disputes should be handled bilaterally.