By Charles Haviland
BBC News, Solukhumbu, Nepal
Namche Bazaar lies on the southern approach to Everest
The days have been cold for the time of year in the bustling Sherpa village of Namche Bazaar.
After a few hours of cool morning sunlight, the mists rise, obscuring the magnificent snow-streaked massif of Kongde across the valley.
Trekkers and climbers, not put off by the weather, are still streaming upwards towards Everest.
And the Nepalese authorities are getting edgy.
On these lower slopes of the mountain, several days' walk from base camp, the police and army have put up at least three extra checkpoints, while armed reinforcements are now on their way up to base camp itself.
The reason for the tightened security is that the Olympic torch is heading to this part of the world.
It is to travel up Everest from the northern, Chinese side which is part of Tibet.
The flame is not being brought to the Nepalese side, but both Nepal and China fear that pro-Tibetan activists could somehow get up the mountain from the southern approach, and make trouble.
Hence the checkpoints. Deep down in the valley, where pine-clad slopes meet Everest's river, the Dudh Koshi, a few friendly police and soldiers rummage through visitors' luggage outside the village of Jorsalle.
The checkpoint is not new, but the searching is.
They are apologetic. They are looking for pro-Tibet paraphernalia or, as the government puts it, "flags, banners, stickers, pamphlets or any audio-visual devices that may harm" Nepal-China relations.
Trekkers and climbers have their bags searched at the checkpoints
The security forces here say they did find such material, carried by someone they believed was Tibetan.
Both he and the material were handed to the military post several hours' walk up the mountain, above Namche.
Up there the next day, the officer-in-charge, Major D B Thapa, told the BBC another man had been sent down from base camp with similar material.
Officials say he is American and was in a group ascending Everest.
"We want the Olympics to be successful," says Major Thapa. "We won't allow any pro-Tibetan activities."
He is tasked with providing security in the national park and this, he says, is his one concern.
Every aspect of this torch-related security operation is highly sensitive, and something on which most people refuse to comment except anonymously.
The Chinese, aware of the torch's disrupted journey so far, are probably more worried than the Nepalese.
In fact, one source in the Nepal security forces said the Chinese government had ordered Nepal to set up the new checkpoints.
Reliable sources in Namche Bazaar say a team of about a dozen Chinese officials, including at least one senior military officer, were in the village about a month ago, carrying out security checks.
Dzopkyos, a cross between a yak and a cow, are used for carrying goods
The village is agog with rumours of similar activity now.
The rumours say a new, small team of Chinese - perhaps police - flew in by helicopter on Wednesday. But they are unproven.
One reason for the speculation is that Tibetan refugees resident in this area were asked by police on Tuesday to put away banners praising the Tibetan spiritual leader, the Dalai Lama, which had been on prominent display.
Sonam Tashi, a genial shopkeeper in his 30s, was born just around the mountain from Namche after his parents arrived from Tibet as refugees.
He says he and his friends would like to stage some kind of demonstration for their country.
He even says their Nepalese Sherpa neighbours, who are close to them in culture, support them morally.
But they are concerned that nothing should disrupt the business that is transacted in these villages during this peak travelling and trekking season.
Police even say local people had some hand in suggesting the extra checkpoints.
"We've got to keep quiet at the moment," Sonam Tashi admits.
There are some accounts of tussles between tourists who had been carrying pro-Tibet materials, and local Nepalese advising them not to.
But there are some Nepalese voices critical of the Chinese, too - albeit anonymously.
One person said he did not see why the peak of Everest had to be closed for the first 10 days of May at China's behest.
Another said that if China had improved its image and human rights record, none of this would have been necessary.
But he still felt Nepal had to respect its neighbour's request.