TONGREN, China — Protests spread from Tibet into three neighboring provinces today as Tibetans defied a Chinese government crackdown, while the Dalai Lama decried what he called the "cultural genocide" taking place in his homeland.

Demonstrations widened to Tibetan communities in Sichuan, Qinghai and Gansu provinces, forcing authorities to mobilize security forces across a broad expanse of western China.

In Tongren, riot police sent to prevent protests set off tensions when they took up positions outside a monastery. Dozens of monks, defying a directive not to gather in groups, marched to a hill where they set off fireworks and burned incense in what one monk said was a protest, according to an Associated Press reporter at the scene.

In a sign that authorities were preparing for trouble, AP and other foreign journalists were ordered out of the Tibetan parts of Gansu and Qinghai provinces by police who told them it was for their "safety."

Meanwhile, police in the Tibetan capital, Lhasa, searched buildings as a Monday deadline loomed for people who took part in a violent anti-Chinese uprising last week to surrender or face severe punishment.

Speaking from India, the Dalai Lama, the spiritual leader of Tibetans, called for an international investigation into China's crackdown on demonstrators in Lhasa, which his exiled government claims left 80 people dead. China's state media has said 10 civilians were killed.

"Whether intentionally or unintentionally, some kind of cultural genocide is taking place," the Dalai Lama said, referring to an influx of Chinese migration into Tibetan areas and restrictions on Buddhist practices — policies that have generated deep resentment among Tibetans.

Tensions also boiled over outside the county seat of Aba in Sichuan province when armed police tried to stop Tibetan monks from protesting, according to a witness who refused to give his name.

The witness said a policeman had been killed and three or four police vans had been set on fire. Eight bodies were brought to a nearby monastery while others reported that up to 30 protesters had been shot, according to activist groups the Tibetan Center for Human Rights and Democracy and the London-based Free Tibet Campaign. The claims could not be confirmed.

Sunday's demonstrations follow nearly a week of protests in Lhasa that escalated into violence Friday, with Tibetans attacking Chinese and torching their shops, in the longest and fiercest challenge to Chinese rule in nearly two decades.

Complicating Beijing's task, the spreading protests fall two weeks before China's celebrations for the Beijing Olympics kick off with the start of the torch relay, which will pass through Tibet.

Though many were small in scale, the widening Tibetan protests are forcing Beijing to pursue suppression while on the run, from town to town and province to province across its vast western region. Sunday's lockdown in Tongren required police imported from other towns, the locals said.

The Chinese government attempted to control what the public saw and heard about protests that erupted Friday. Access to YouTube.com, usually readily available in China, was blocked after videos appeared on the site Saturday showing foreign news reports about the Lhasa demonstrations, montages of photos, and scenes from Tibet-related protests abroad.

Television news reports by CNN and the BBC were periodically cut during the day, and the screens went black during a live speech by the Dalai Lama carried on the networks.

China's communist government had hoped Beijing's hosting of the Aug. 8-24 Olympics would boost its popularity at home as well as its image abroad. Instead the event already has attracted the scrutiny of China's human rights record.

Thubten Samphel, a spokesman for the Dalai Lama's government, said multiple people inside Tibet had counted at least 80 corpses since the violence broke out Friday. He did not know how many of the bodies were protesters. The figures could not be independently verified because China restricts foreign media access to Tibet.

In Lhasa, hundreds of armed police and soldiers patrolled the streets on Sunday. Hong Kong Cable TV reported some 200 military vehicles, carrying 40 to 60 armed soldiers each, drove into the city center.

Footage showed the streets were mostly empty other than the security forces. Messages on loudspeakers warned residents to "discern between enemies and friends, maintain order" and "have a clear stand to oppose violence, maintain stability."

James Miles, a BBC correspondent in Lhasa, said troops carrying automatic rifles were "letting off the occasional shot." He said people were scared to come out of their homes for fear of being hit by a bullet.

Westerners who were told to leave Lhasa and arrived by plane in the city of Chengdu said they heard gunshots and explosions throughout Saturday and overnight.

"The worst day was yesterday. It was completely chaotic. There was running and screaming in the street," said Gerald Scott Flint, director of the medical aid group Volunteer Medics Worldwide, who had been in Lhasa four days. Flint said he could see fires burning six or more blocks away.

Tashi Wangdi, president of the Office of Tibet that represents the Dalai Lama in New York, called the departure of tourists worrisome.

"I think there will be total blackout of information to the outside world," he said. "Our worry is they will be more brutal and will use more force now."

The unrest in Tibet began March 10 on the anniversary of a 1959 uprising against Chinese rule of the region. Tibet was effectively independent for decades before communist troops entered in 1950.

The Tibetan communities living far outside what China calls modern Tibet are parts of former provinces of past Tibetan kingdoms, and many inhabitants still revere the Dalai Lama.

"We want freedom. We want the Dalai Lama to come back to this land," said a monk from Rongwo in Tongren. The monks display his pictures, though they have been ordered to remove them.

Inspired by the protests in Lhasa, monks and Tibetans in the town of Xiahe in Gansu province staged two days of protests, one peaceful in which they raised Tibetan national flags, the other in which government offices were smashed and police tear-gassed the crowd of more than 1,000.

Authorities clamped a curfew on Xiahe overnight. Patrols of riot police, in black uniforms, helmets and flak jackets, and armed police in green uniforms carrying batons marched through the town Sunday in groups of 10 and 20.

Smaller protests were reported in two other nearby towns, witnesses said, in both cases drawing truckloads of armed police.

In the Gansu provincial capital of Lanzhou, more than 100 Tibetan students staged a sit-down protest on a playing field at Northwest Minorities University, according to the activist group Free Tibet.

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Tini Tran reported from Beijing. Associated Press writers David Wivell in Xiahe and Carley Petesch in New York contributed to this report.

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On the Net:

International Campaign for Tibet: http://www.savetibet.org

Chinese official news agency (in English): http://www.chinaview.cn

Tibet Daily: http://www.tibetdaily.com