BEIJING — Tibet's governor promised leniency to anti-Chinese protesters who turned themselves in before the end of today — and harsh consequences for those who don't — while troops fanned out to quell sympathy protests that have spread to three neighboring provinces.

Champa Phuntsok said last week's violent demonstrations in the regional capital of Lhasa left 16 dead and dozens injured. Unconfirmed reports from Tibetan exile groups put the death toll at 80, a claim he denied.

The uprising, the fiercest against Chinese rule in the region in almost two decades, has embarrassed China's communist government and undermined its efforts to have an unblemished run-up to the Beijing Olympics.

The ensuing crackdown, meanwhile, led the Dalai Lama, Tibetans' exiled spiritual leader, to decry what he called "cultural genocide" in his homeland and call for an international investigation.

He also expressed helplessness in the face of the surrender demand. The Washington, D.C.-based International Campaign for Tibet said residents were fearful of a military sweep after the deadline at midnight on Monday.

The Tibet governor described a scene of chaos throughout Lhasa on Friday with "people engaged in reckless beating, smashing, looting and burning." Shops, schools, hospitals and banks were targeted and bystanders were beaten and set on fire, he said.

"No country would allow those offenders or criminals to escape the arm of justice and China is no exception," said Champa Phuntsok, an ethnic Tibetan installed in the governor's role.

"If these people turn themselves in, they will be treated with leniency within the framework of the law," he said. "If these people could provide further information about the involvement of other people in those crimes, then they could be treated even more leniently."

Otherwise, he added, "we will deal with them harshly."

He said he did not know if anyone had surrendered so far. A woman from the duty office of Lhasa's Public Security Bureau and a man from the publicity department of the city's Communist Party Committee said they had no idea about the situation.Meanwhile, security forces were mobilizing across a broad expanse of western China, where demonstrations were springing up in Tibetan communities in the provinces of Sichuan, Qinghai and Gansu.

A witness in Sichuan said that government troops had moved into a county in Aba prefecture, where clashes between monks and police broke out Sunday with unconfirmed reports of as many as seven killed.

"There are troops that moved into Maerkang County," said a clerk at the Jinchuan Hotel, who asked not to be further identified.

In Qinghai, riot police sent to prevent protests set off tensions Sunday when they took up positions outside a monastery in Tongren. Dozens of monks marched to a hill where they set off fireworks and burned incense in what one monk said was a protest.