Rescuers worked to clear a snow-blocked road and free 86 tourists, including 13 foreigners, stranded on Monday at the northern base camp of Mount Qomolangma in the Tibet autonomous region.

An "unexpected" snowfall delivered by Cyclone Phailin hit southwestern parts of Xigaze prefecture on Sunday, trapping tourists at the base camp.

Local authorities said many of the 13 foreigners were Japanese.

The base stands 5,200 meters above sea level, and the oxygen content of the air is about 40 percent of that at sea level, causing occasional cases of altitude sickness among visitors. So far, no casualties or injuries have been reported among the stranded tourists.

Snow continued to fall and hindered rescue operations on Monday afternoon, according to rescuers.

The average thickness of the snow was more than 45 cm, and drifts reached up to 60 cm at Rongbuk Monastery close to the base.

Weather forecasts predict continued cloud cover over the next three days, with temperatures remaining between -2 C and 14 C.

Mobile phone communications are working only intermittently, according to officials in Dingri county, Xigaze prefecture.

"Four vehicles are clearing the road. The trapped tourists have enough to eat and they remain emotionally stable," said Tian Shixin, a publicity official of the Xigaze government.

Tian added that officials of the autonomous region had activated emergency plans and three teams are leading the rescue operation.

By press time, the road to the Rongbuk Monastery has been cleared and some tourists had been rescued, according to a press release of the government of Tibet autonomous region.

Tsetop, deputy head of the county government in Dingri, where the base is situated, said he is heading the team to clear the snow-blocked road.

The road connecting the base to Dingri county town, at an elevation of 4,300 meters, is about 115 km long.

"We will do our utmost to reach those who are stranded and clear the road as soon as possible," said Tsetop.

He added that about 15 staff members from the police station at the base are helping to cater for the tourists, who might be spending the night in tents. Accommodation conditions around the base are poor, consisting mostly of large tents and low-grade buildings.

The police office established in 2008 is equipped with an oxygen generator and oxygen cylinders, and there are police officers who can communicate in English and Tibetan.

According to Tian, the tourists were trapped because the snowfall was unexpected. Normally, spring and autumn are the best times to visit the base camp.

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