Dozens of Americans and Canadians are among hundreds of people who are missing following a deadly flash flood and mudslide near the Nepal-Tibet border, Nepali authorities say.

More than 150 people are so far known to have died, according to the authorities.

The US State Department said it was aware that Americans were impacted by Wednesday’s floods but did not provide numbers.

It added that the US embassy in Nepal is working closely with local tour agencies and authorities to assist affected Americans, a spokesperson said.

Canada’s foreign office said it was also monitoring developments and was ready to provide assistance if needed.

According to Nepal police, more than 500 tourists are missing – including 466 who are foreign nationals and from 28 different countries.

They include 54 people from the US, more than 100 from India, 33 from the UK and more than 100 from Nepal.

The US State Department did not provide figures or additional details regarding the Americans affected for privacy reasons.

A further 24 Canadians are also missing, a Nepal Tourist Board spokesperson said.

Canada’s Prime Minister Mark Carney said his government was closely following the situation.

“As rescue efforts continue, Canada stands ready to provide support,” Carney wrote on X.

The prime minister said all Canadians in the region should sign up for Registration of Canadians Abroad, a free service that lets the federal government contact and assist citizens during an emergency in other countries.

Canada’s foreign affairs office said that 820 Canadians are registered as being in Nepal and five Canadians are registered as being in the Tibet Autonomous Region, China, citing the Registration of Canadians Abroad system.

The office emphasised that the numbers are only estimates as registration is voluntary and includes registrants that might not have made travel plans.

“The Department is aware of Canadians who have been affected by the floods,” the Global Affairs Office said in a statement to the BBC.