A Tibetan nun is believed to have died after setting herself on fire to protest China's rule over the Himalayan region and to voice support for the Dalai Lama, rights groups and media said.

Yeshi Khando walked around the Kardze Monastery in a type of prayer that is common in Tibetan Buddhism, and then set herself alight on Wednesday near the Ganzi county police station, the British-based Free Tibet group, the International Campaign for Tibet (ICT) and US-funded Radio Free Asia (RFA) said.

The 47-year-old nun "called for the return of the Dalai Lama and also for his long life," RFA reported, citing anonymous sources and referring to Tibet's exiled spiritual leader.

"She also called for the freedom for Tibet."

RFA said that those present do not believe Khando survived.

Hwewas quickly removed by security forces and her family was summoned by the police on Thursday, Free Tibet said.

This week, Tibet's Communist Party Secretary Chen Quanguo ordered Tibetan monasteries to display Chinese flags and to vow to assess Buddhist monks and nuns for their "patriotism".

It is not clear on what grounds the assessments would be made. China often uses terms such as "patriotic" and "harmonious" to mean allegiance to political authorities.

There have been more than 130 cases of Tibetans setting themselves on fire in China since 2009, most of them fatal, both the ICT and RFA said.

Self-immolations peaked in the run-up to the ruling Communist Party's pivotal five-yearly congress in November 2012, and have become less common since.

Many Tibetans in China accuse the government of religious repression and eroding their culture, as the country's majority Han ethnic group increasingly moves into historically Tibetan areas.

Beijing condemns the acts and blames them on the Dalai Lama, saying he uses them to further a separatist agenda.

The Dalai Lama, a Nobel Peace laureate who has lived in India since 1959 after a failed uprising in Tibet, has described the self-immolations as acts of desperation that he is powerless to stop.