BEIJING — China is denying mountaineers permission to climb its side of Mount Everest this spring, a move that reflects concerns by the communist government that Tibet activists may try to disrupt its plans to carry the Olympic torch up the world's tallest peak.

In recent days, everyone from the U.S. government to rights groups and George Clooney have urged China to tackle issues as varied as its restrictions on religion; the poor working conditions of migrant labor; Beijing's oil purchases from Sudan to fuel the Darfur crisis; and Tibet.

The Everest restrictions were contained in a letter the government's mountaineering association sent this week to expedition companies. It comes as China's much criticized rule of Tibet, long a hot-button issue, is heating up, joining a growing list of other topics that pressure groups want Beijing to confront before the Aug. 8-24 Olympics.

Chinese police fired tear gas to clear Buddhist monks protesting for a second day Tuesday in Lhasa, the U.S.-funded broadcaster Radio Free Asia reported. In a sign of growing concerns over Olympic security, Beijing said Wednesday that the ruling Communist Party's law enforcement czar was named to a three-man committee overseeing Olympic preparations.

Foreign Minister Yang Jiechi also testily chastised critics trying to leverage the Olympics to draw attention to human rights violations and other issues. Those who "want to tarnish the image of China," Yang said in a rare televised news conference, "they will never get their way."

With less than five months to go to the games — and three weeks before the Olympic flame arrives in Beijing — events are taking on a harder political tone, and the criticism has put the government on the defensive at a time it hoped to be basking in praise.

"They see this as somewhat hostile and mainly because it's pressure to change, and that provokes a hostile reaction from them," said Susan Brownell, an American expert on China sports scene who is spending a year at Beijing Sports University.

Annexed by Chinese troops 58 years ago but with a resilient exile community led by the Nobel Peace Prize laureate the Dalai Lama, Tibet has been a concern for Beijing Olympic security planners and crisis managers for months. In the past year, Tibet activists have unfurled banners at Everest base camp and the Great Wall, calling for Tibet's independence.

Bringing the Olympic flame to the summit of Everest is shaping up to be one of the grandest — and most politicized — feats of the already politicized Beijing games.

The 29,035-foot peak is battered by harsh weather and wreathed in thin oxygen, presenting a physical and technical challenge to the torch crews. The mountain also straddles the political border between Chinese-controlled Tibet and Nepal, home to Tibetan exiles and activists.