The postmaster, however, seemed to have been infected by the Chinese officials around him, refusing to give much information beyond the fact that it would cost five 5 yuan (72 U.S. cents) - EVEREST BASE CAMP - Sub-zero temperatures and altitude sickness were bad enough, but a lack of information about just when a special Olympic flame would start up Mount Everest made journalists doubly miserable at Base Camp on Tuesday.

More than 24 hours after arriving at the foot of the world's highest mountain, 10 foreign and 19 Chinese journalists had no clearer idea of when the assault on the summit from Tibet would begin, if it had not already.

The Everest flame is separate from the globetrotting Olympic torch that was paraded in Vietnam's Ho Chi Minh City on Tuesday evening, the last international leg of a relay that has been dogged by protests and counter-protests over Tibet.

Officials are determined that this most prestigious stage of the global parade will not be spoilt by demonstrations.

All that was heard at Base Camp was the official mantra -- "the torch will go up Mount Qomolangma on a day in May when the weather conditions are most suitable" -- and educated guesses as to exactly when -- Wednesday's 100-day countdown to the Beijing Games and Thursday's Labour Day holiday being the favourites.

"We are trying our best to give you information," said Liu Xuan, deputy director of the Tibet Information Office at the only press briefing on Tuesday. "We are hiding nothing."

Off the record, several of the large band of minders and interpreters accompanying the media admitted that there was an official silence because of security concerns.

A Japanese journalist who attempted to walk towards Base Camp proper on Tuesday afternoon was turned back by an armed security official.

GRIM

No other expeditions have been allowed on the northern, Tibetan side until the torch has reached the top of the Everest.

Teams of climbers on the southern, Nepali side have had most of their communication equipment removed and will not be able to summit until mid-May, according to various climbing websites.

Nepal deported a U.S. national and banned him from climbing in the country for two years after he was found carrying a pro-Tibet banner on an expedition to the Everest last week, a Nepal Tourism Ministry spokesman said on Tuesday.

The temporary media trailer camp, dominated by the imposing pyramid of the 8,848-metre peak, has comforts that many Everest expeditions could only have dreamed of.

But for those unused to sub-zero temperatures, a whipping wind and the most basic of sanitary facilities, it can be grim: especially after a rise from 54 metres above sea level to more than 5,000 metres in less than four days.

Two victims of altitude sickness left the camp on Monday evening and, despite an ambulance crashing and causing a minor head wound to a nurse, they were said to be "well" in the town of Shigatse.

One of the two, Hong Kong television journalist and sometime-actor Wang Xi wanted to return to Base Camp on Wednesday, according to his colleague.

As the day wore on, concern about altitude sickness turned the routine greeting "How are you?" into a serious enquiry, and admonitions to "drink more water" and "get plenty of rest" bounced back and forth across the camp.

The Mount Qomolangma post office, which claims to be the highest in the world, was doing brisker trade on Tuesday than it has since foreigners were banned from Tibet after deadly riots in the regional capital, Lhasa, last month.

The postmaster, however, seemed to have been infected by the Chinese officials around him, refusing to give much information beyond the fact that it would cost five 5 yuan (72 U.S. cents) to have him put his official stamp on a postcard.