The search for four South Korean trekkers and three Nepalis swept away by an avalanche in the Himalayas almost a week ago was suspended Thursday as conditions made further operations too risky.

The trekkers were descending near Annapurna base camp in Nepal, around 3,230 metres (10,600 feet) above sea level, when the avalanche struck last Friday.

"The situation has become too risky for the search teams to continue," said Dandu Raj Ghimire, chief of Nepal's tourism department.

"We will resume when the conditions allow and the mass of snow begins to melt," he told AFP.

Officials said some snow could thaw in two weeks if the weather is sunny, but it could take up to a month for most of it to melt.

The valley in the Annapurna mountain region where the avalanche struck
The valley in the Annapurna mountain region where the avalanche struck Nepalese Army / Handout

On Wednesday, a search team of Nepal Army specialists, several South Korean personnel, and locals dug into an area where signals from various tracking devices had been recorded.

Sniffer dogs were also used.

But fresh avalanches since the initial fall have piled on the snow, hampering digging and adding to the risks for search parties.

"There is a chance that a bigger avalanche might be triggered," said Suraj Paudyal, rescue coordinator with Simrik Air, who has been involved in the operation.

Thousands of trekkers visit Nepal every year for its stunning views of the Himalayas and routes lined with picturesque villages.

The Annapurna region is particularly popular among tourists, with 172,720 visiting the area in 2018.