Beijing  - Tibetans in China have staged several small protests in support of the exiled Dalai Lama in the last few days, including at least one on Saturday's anniversary of rioting last year, Tibetan exile groups reported on Sunday.

Police detained three young Tibetan men in Kardze (Ganzi) prefecture, in China's south-western province of Sichuan, after they shouted slogans including "long live the Dalai Lama" and "independence for Tibet" on Saturday, the Tibetan website Phayul. com quoted the Voice of Tibet radio station as saying.

Three Tibetan teenage girls were also arrested on Wednesday and a lone protester was detained on Thursday in Kardze the report said.

The Tibetan government-in-exile on Sunday reported several other protests in recent days, including one in Kardze and one near the Sumdo monastery in Sichuan's Ngaba (Aba) prefecture on Tuesday.

Police questioned monks from Sumdo after slogans supporting the Dalai Lama were pasted in and around the monastery, it said.

"Tibet is virtually under undeclared martial as the Chinese government has deployed massive paramilitary forces across the length of Tibet," the Tibetan government-in-exile said on its official website.

In a separate report, the website quoted sources as saying the area around the monastery town of Rebkong in Qinghai province was "under military siege" and that authorities had temporarily banned the sale of new SIM cards for mobile phones.

In Lhasa, the capital of China's Tibet Autonomous Region, where rioting broke out on March 14 last year, troops in full battle dress reportedly patrolled largely deserted streets in the city centre on Saturday.

The Hong Kong-based South China Morning Post and Japan's Kyodo news agency reported an "intimidating" atmosphere in Lhasa on Saturday.

Convoys of up to 20 armoured vehicles "drove slowly down main streets, with marksmen on the vehicles covering both sides of the street", the newspaper said.

Anyone in Lhasa without a local identity card faced questioning and possible detention, while major monasteries were sealed off, it said.

The newspaper said police operated late-night road blocks in the city centre while "shops and entertainment venues were ordered to shut as early as 10 pm."

It quoted local sources as saying that a small protest broke out around Lhasa's Sera Monastery on Monday, one day before Tuesday's 50th anniversary of a failed Tibetan uprising against Chinese rule.

Two military vehicles of up to 100 armed police in anti-riot gear were outside the entrance to Sera on Friday, it said.

US-funded Radio Free Asia reported that police seized a single Tibetan protestor on Tuesday after he shouted slogans in support of the exiled Dalai Lama and Tibetan independence in the town of Lithang in Sichuan.

Paramilitary police sealed off almost all Tibetan areas of China to foreign journalists and tourists since Tuesday while the government has tightened border security, stepped up a propaganda drive and cut off some text-messaging and other mobile telephone services in Lhasa and other Tibetan areas. dpa