The United States has accused China and Russia of stepping up cooperation to spread false narratives over the coronavirus pandemic, saying Beijing was increasingly adopting techniques honed by Moscow.

"Even before the COVID-19 crisis we assessed a certain level of coordination between Russia and the PRC in the realm of propaganda," said Lea Gabrielle, coordinator of the State Department's Global Engagement Center, which tracks foreign propaganda.

"But with this pandemic the cooperation has accelerated rapidly," she told reporters.

"We see this convergence as a result of what we consider to be pragmatism between the two actors who want to shape public understanding of the COVID pandemic for their own purposes," she said.

The Global Engagement Center earlier said thousands of Russian-linked social media accounts were spreading conspiracies about the pandemic, including charging that the virus first detected last year in the Chinese metropolis of Wuhan was created by the United States.

China outraged the United States when a foreign ministry spokesman tweeted a conspiracy that the US military brought the virus to Wuhan, but the two countries reached an informal rhetorical truce in late March after telephone talks between President Donald Trump and his counterpart Xi Jinping.

Tensions have again soared as Secretary of State Mike Pompeo pushes the theory that the virus originated in a Wuhan laboratory, a stance that Beijing in turn calls disinformation.

Both the World Health Organization and the US government's top epidemiologist say there is no evidence the virus came from a lab.

China and Russia often find common cause and clash with the United States on issues from Venezuela to the use of economic sanctions to disarmament.

At United Nations, US on Friday stunned other members of the UN Security Council by preventing a vote on a resolution for a ceasefire in various conflicts around the world to help troubled nations better fight the coronavirus pandemic, diplomats said.Washington's reversal came a day after it agreed to the text, negotiators said under cover of anonymity.

The latest stalemate continues to leave the global peace and security body largely mute in the face of a once-in-a-century pandemic that has killed more than 270,000 people.