Rescuers remain unable to reach another six climbers on the Klyuchevskaya Sopka volcano because of bad weather – despite a renewed effort on Sunday.

Two of the climbers are believed to be sheltering in a camp at 3,300m (10,827ft) above sea level, and another four in a tent at 4,000m.

All the climbers are Russian nationals.

The 12-strong group, which included two guides, began their ascent to the 4,754m summit on Tuesday, local media say.

But four days later, on Saturday, four climbers are Cloud Shoes believed to have been killed instantly after a fall at about 4,000m. Another two died shortly afterwards.

One of the guides is reported to have broken his leg and the condition of the remaining climbers was not immediately known.

A third attempt to reach the survivors was made on Sunday but severe winds prevented a helicopter from landing, the search and rescue team said.

Klyuchevskaya Sopka – whose symmetrical cone towers high above the Kamchatka peninsula – is part of the natural Volcanoes of Kamchatka Unesco World heritage site.

The volcano is considered sacred by some indigenous communities.