The US has thrown its support behind negotiations on a treaty to curb plastic pollution, ending a key holdup in international efforts to clean up the planet's oceans and save marine life.

On a visit to the UN Environment Programme in Nairobi, Secretary of State Antony Blinken said the US would back talks in the Kenyan capital in February on a treaty to address plastic.

"Our goal is to create a tool that we can use to protect our oceans and all the life that they sustain from growing global harms of plastic pollution," Mr Blinken said.

"As we know, our health - our survival - is bound up in the health of our oceans. We have to do more to protect them," he said.

About eight million tonnes of plastic end up in the oceans each year, killing or injuring one million birds and more than 100,000 marine mammals, according to UN figures.

Mr Blinken's statement is the latest US effort to ramp up environmental protection under President Joe Biden, who has made the fight against climate change a key domestic priority.

Likely mindful of political realities in divided Washington, where treaties need ratification by the Senate, Mr Blinken called for a plastic treaty in which countries would come up with their own plans of action.

The US, however, has seen bipartisan calls to clean up oceans with former president Donald Trump signing an act aimed at curbing plastic pollution in the oceans.

But environmentalists say that the previous administration stymied international efforts by opposing a treaty and blaming the problem squarely on China - a major source of plastic processing but of material often coming from the West.

In 2019, the US did not join around 180 governments which agreed in Geneva to create a legally binding framework to regulate plastic waste.

The US did not vote as it is not party to the Basel Convention, a UN treaty reached in 1989 that regulates the movement of hazardous waste.