A thousand European Union citizens in Nepal are still unaccounted for, nearly a week after a massive quake that hit during the peak trekking season, the EU ambassador to Nepal said Friday.

Most were trekking in the remote Langtang mountain range near the epicentre or in the Everest region, Rensje Teerink told journalists in Kathmandu.

"They are missing but we don't know what their status is," she said.

"Many were in the Langtang area and some were in the Lukla area," she added, referring to the small Himalayan airstrip known as the gateway to Everest.

Another EU official said on condition of anonymity that the majority were likely to be found safe and well but that their status was currently unknown given the difficult terrain and lack of access to affected regions.

The 7.8-magnitude quake that hit on Saturday triggered an avalanche at Everest base camp that left 18 people dead on the world's highest peak.

There have also been unconfirmed reports of large avalanches flattening villages in Langtang, a remote region north of Kathmandu that rescuers have struggled to reach.

Local newspaper reports say dozens of foreigners have been evacuated from Langtang.