Tensions between the United States and China have spiked in recent weeks, but White House economic adviser Larry Kudlow has assured that the beleaguered accord is not on the verge of collapse.

The US-China phase one trade deal reached in January is not falling apart and the two countries are still working to implement it, Kudlow said on Friday, but President Donald Trump added that he was not "thrilled" with the agreement, and suggested that he could cut ties with the world's second-largest economy.

In another major development, China issued a statement calling on all UN member states to "actively fulfill their financial obligations to the United Nations," stressing that Washington owes the organization more than $2 billion.

"As of May 14, the total unpaid assessments under the UN regular budget and peacekeeping budget amount to 1.63 billion and 2.14 billion US dollars respectively," the Chinese statement said, citing a report from UN Secretary-General's office and a meeting held on Thursday.

Including arrears that stretch back several years, "the United States is the largest debtor, owing 1.165 billion and 1.332 billion US dollars respectively," China added.

The US is the biggest contributor to the UN budget, paying 22 per cent of its annual running costs, a bill which adds up to around $3 billion, and 25 per cent of its peacekeeping operations, which amount to some $6 billion a year.

In an interview with Fox Business Network, Trump said he was very disappointed with China's failure to contain the coronavirus outbreak and that the pandemic had cast a pall over the trade deal with Beijing that he considers a major achievement.

The Chinese are working toward holding up their end of the agreement, which calls for Beijing to boost purchases of American farm goods, manufactured products, energy and services by $200 billion over two years, Kudlow said.

"They're a little slow on the commodity purchases. I think that has a lot to do with market and economic positions," he said.

Kudlow's comments came at the end of a week of complaints from Trump about China's early handling of the coronavirus outbreak, and separate steps by his government to crack down on China's blacklisted telecoms equipment giant Huawei Technologies and curb US investment in some Chinese companies.

On Thursday, Trump said he now feels differently about the trade deal and may even cut economic ties with Beijing.

Asked at a White House Rose Garden event on Friday whether he is planning to impose additional tariffs on China or tear up the trade deal, Trump said: "I don't want to talk about it.

I can say China is buying a lot of our product. But the trade deal, the ink was barely dry when this (the virus) came in from China, so it's not like we're thrilled."

"We have other issues with China, and of course the origin of the virus ... but with respect to the trade deal, it is continuing, absolutely," Kudlow said.