Human rights groups are reporting increased security in and around Tibet
Foreign tourists planning to visit Tibet have been told by travel agencies that the region has been closed to outsiders until the end of March.
The month marks the 50th anniversary of the escape into exile of the Tibetan spiritual leader, the Dalai Lama.
In March last year, Tibet witnessed a wave of violent anti-China protests – the worst unrest there for 20 years.
Tibetan exiles are planning to boycott their own New Year celebrations on Wednesday in protest at Chinese rule.
The Dalai Lama has called for Tibetans not to celebrate New Year, or Losar, partly in memory of those killed or jailed in a crackdown after last year’s riots.
China said at least 18 people were killed during the unrest. Rights groups and activists say about 200 people were killed and several hundred more are still missing.
China does not allow foreign journalists unrestricted access to Tibet or restive areas surrounding it, making it extremely difficult to verify reports from the region.
“This year it’s going to be observed as a day of prayer in memory of all the Tibetans who died and all those who are still suffering under Chinese rule,” Tenzin Taklha, the Dalai Lama’s India-based spokesman, was quoted by AFP as saying.
Groups representing Tibetans-in-exile have described the move as an “act of civil disobedience” against Chinese “repression”.
The defiant stance comes amid reports by human rights groups of increased security in Tibet and neighbouring Tibetan-populated regions of western China.
Last year’s protests took the Chinese authorities by surprise, and the BBC’s James Reynolds in Beijing says the state wants to make sure that there is no repeat.
The BBC has also been told privately by senior Chinese sources that no foreign journalists will be allowed into the region during March.
Travel agencies say that permits already issued to foreigners have been cancelled.
However, Chinese foreign ministry official Ma Zhaoxu told the BBC that Tibet currently enjoys social stability and growth, and that foreigners can apply to visit the region through normal channels.
China has ruled Tibet since 1951 and views it as an integral part of its territory.
It believes that the Chinese Communist Party liberated the Tibetan people from the oppressive feudal rule of the Dalai Lama, following a failed 1959 uprising against Chinese rule.
On 28 March 1959 the Communist Party announced the dissolution of the existing local government in Tibet – following the Dalai Lama’s flight a few days’ beforehand.
China says that this move freed about one million Tibetans from serfdom and slavery.
But to Tibetan groups in exile, the events of March 1959 and the exile of the Dalai Lama were a tragedy.
The Dalai Lama has said he does not want independence for Tibet, only meaningful autonomy.