NEW DELHI (REUTERS, AFP) - An avalanche at Mount Everest base camp triggered by a massive earthquake killed at least 10 people on Saturday, including foreign climbers, a Nepalese official said.

"We don't have the details yet, but 10 have been reported dead so far, including foreign climbers," Gyanendra Kumar Shrestha from Nepal's tourism department told AFP.

The avalanche buried part of the base camp for climbers bound for Everest, he said.

April is one of the most popular times to scale Everest, before rain and clouds cloak the loftiest Himalayan mountain at the end of next month.

Measuring a potentially devastating 7.9 magnitude, the quake struck west of Kathmandu on Saturday and flung tremors through northern India, causing buildings to collapse.

The death toll from the strongest quake to hit Nepal for 81 years rose to 688, most in the Kathmandu Valley and including 181 in the capital, Nepalese interior authorities said.

Romanian climber Alex Gavan said on Twitter that there had been a "huge avalanche" on Everest and "many, many" people were up on the mountain. "Running for life from my tent," he said.

Another climber, Daniel Mazur, said Everest Base Camp had been "severely damaged" and his team was trapped. "Please pray for everyone," he said on his Twitter page.

Mohan Krishna Sapkota, joint secretary in the Nepalese tourism ministry, said the government was struggling to assess the damage on Everest because of poor phone coverage.

"The trekkers are scattered all around the base camp and some had even trekked further up," Sapkota said. "It is almost impossible to get in touch with anyone."

Choti Sherpa, who works at the Everest Summiteers Association, said she had been unable to call her family and colleagues on the mountain. "Everyone is trying to contact each other, but we can't," she said. "We are all very worried."

An avalanche in April 2014 just above the base camp killed 16 Nepali guides.