The United States and North Korea hold "the primary responsibility" for de-escalating tensions and negotiating peace on the Korean Peninsula, not China, Beijing's UN ambassador said on Monday.

Liu Jieyi said that if Washington and Pyongyang refuse to reduce tensions and hold new talks as called for in UN Security Council resolutions, "then no matter how capable China is, China's efforts will not yield practical results because it depends on the two principal parties."

The Trump administration has accused China of failing to rein in North Korea's nuclear and ballistic missile programmes and warned of possible economic reprisals on Beijing, which is responsible for 90 per cent of trade with the northeast Asian nation.

In comments clearly directed at the US and North Korea, Liu said instead of complying with Security Council calls to de-escalate tensions and re-launch six-party negotiations, tensions have heightened as a result of new missile tests, statements that "all options are on the table," and deployment of the U.S. THAAD anti-missile system.

And in criticism aimed specifically at the United States, the Chinese ambassador said implementation of Security Council resolutions is also being hampered by unilateral sanctions and "preconditions put to starting the dialogue" with Pyongyang.

The Trump administration has declared that all options, including a targeted military strike, are on the table to block North Korea from carrying out threats against the United States and its allies in the region. But a pre-emptive attack isn't likely, U.S. officials have said, and the administration has been pursuing a strategy of pressuring Pyongyang through new unilateral sanctions and appealing to China to use its influence.

Pyongyang's two recent successful tests of intercontinental ballistic missiles have created even more urgency as the U.S. administration seeks to stop its efforts to master the complex process of mounting a nuclear warhead capable of hitting the United States.

As for resuming talks, which stalled in 2009, the United States has said it won't enter negotiations with North Korea until the country proves it will move toward abandoning its nuclear weapons programme.

Trump tweeted today: "We will no longer allow this to continue. China could easily solve this problem!" And U.S.

Ambassador to the United Nations Nikki Haley joined in the criticism, saying China "must decide whether it is finally willing to take this vital step" of getting tough on the North.

Liu, at a news conference marking the end of China's presidency of the Security Council in July, tried to shift the responsibility for engaging North Korea from Beijing to Washington and Pyongyang.

"They hold the primary responsibility … to start moving in the right direction, not China," he said.