BEIJING - TIBET'S top government official Qiangba Pingcuo denied on Saturday that the regional capital Lhasa was under martial law.

But he declined to respond to questions whether there had been shootings or deaths.

'We will handle this according to the law,' he told reporters on the sidelines of the annual session of parliament.

The protests, which spread outside Tibet into other areas of China, came amid a growing international campaign by Tibetans to challenge Beijing's rule of the Himalayan region ahead of the Olympic Games in August.

China's state-run Xinhua news agency confirmed that police had fired warning shots and used tear gas to disperse the demonstrating crowd in the heart of old Lhasa.

Many police officers were badly injured in clashes in Tibet's capital Lhasa while also reporting that a mosque and other buildings had been set on fire.

Xinhua news agency blamed Friday's unrest on rioters 'carrying backpacks filled with stones and bottles of inflammable liquids, some holding iron bars, wooden sticks and long knifes.' It reported cases of burn injuries.

The agency reported the violence had died down Friday night, but added that 'local residents are not sure what will happen tomorrow'.

Several people lost their lives and many others were injured in Lhasa on Friday, an official at the city's medical emergency centre said, with Radio Free Asia reporting at least two people had been killed by Chinese bullets.

Dense smoke covered central Lhasa. Police cordoned off several sections of downtown Lhasa and were on the lookout for new violence, according to the Xinhua report.

The regional government 'took emergency measures to rescue residents under attack,' Xinhua said, including reinforced protection of schools, hospitals and gas stations.

Local government imposed heightened control on Lhasa's main streets Friday night, while sending out a 'sabotage' warning via TV, calling on viewers to take unspecified precautions.

Xinhua said the violence had died down early on Saturday, but that burning wreckage in the streets was left from the previous day's clashes.

UN calls for calm
The tense situation triggered a United Nations call for calm.

'We urge that care be taken by all concerned to avoid confrontation and violence,' said UN chief Ban Ki Moon's press office.

The United States, Britain and other European states expressed concern over the violence, with the White House calling on Beijing to 'respect Tibetan culture' and the US ambassador here asking officials to 'act with restraint'.

Tibet's exiled spiritual leader, the Dalai Lama, said the protests were a result of public resentment of the 'brute force' employed by China to maintain control of the region for more than 50 years.

'I therefore appeal to the Chinese leadership to stop using force and address the long-simmering resentment of the Tibetan people through dialogue with the Tibetan people,' he said in a statement issued from his base in India.

'I also urge my fellow Tibetans not to resort to violence.'

But Tibet's Communist government blamed groups close to the Dalai Lama for 'organised, premeditated and masterminded... sabotage,' Xinhua said early Saturday.

A spokesman for the Dalai Lama, Chhime R. Chhoekyapa, reacted swiftly, calling the Chinese accusation 'absolutely baseless.'

Protests
More than 100 Buddhist monks kicked off the protests early Friday, which quickly attracted hundreds of other Tibetans and saw one of the biggest markets in Lhasa as well as cars set ablaze, foreign tourists and rights groups said.

At least 900 people rioted in Lhasa, and more than 1,000 security forces were sent in to quell the unrest, the Free Tibet Campaign said, citing Tibetans in the city.

The official at the medical emergency centre in Lhasa said staff were overwhelmed by the number of victims.

'We are very busy with the injured people now - there are many people injured here. Definitely some people have died, but I don't know how many,' a female official at the centre said by phone.

Radio Free Asia, a US-funded broadcaster, said there had been terrible clashes between Tibetans and Chinese security forces.

'Chinese police fired on rioting Tibetan protesters in Lhasa on Friday, killing at least two people, as Tibetans torched cars and shops and anti-Chinese demonstrators surged through the streets,' it said.

The unrest spread outside Lhasa, with monks leading a rally of up to 4,000 people in Xiahe, Gansu province, the site of one of Tibetan Buddhism's most important monasteries, the Free Tibet Campaign said, citing Tibetan sources there.

The unrest followed three days of protests by hundreds of monks in Lhasa, India and elsewhere around the world that marked the anniversary of a failed Tibetan uprising against Chinese rule in 1959.

China has ruled Tibet since 1951, a year after sending troops in to 'liberate' the region from what it said was feudal rule. Tibet's spiritual leader, the Dalai Lama, fled to India following the failed 1959 uprising.

Tibetan rights groups have vowed to pile intense pressure on China over its controversial rule of the region in the lead-up to the Summer Olympic Games, when the world's spotlight will be put on the nation's communist rulers.

The protests are the biggest since 1989, when current Chinese President Hu Jintao was the Communist Party chief of Tibet.

Mr Hu is due to be re-elected on Saturday by the nation's rubber-stamp parliament as president for another five years. -- AFP, REUTERS