BEIJING - A leading Tibetan environmentalist has been jailed for subversion, the third such verdict amid an apparent crackdown on intellectuals in the Himalayan region, activists said Sunday.

Rinchen Samdrup, 44, was sentenced to five years in prison on Saturday for attempting to incite subversion by a court in Tibet`s Chamdo region, poet and rights activist Woeser said on her blog.

The verdict comes after his brother Karma Samdrup, 42, a noted art and antique collector and philanthropist, was sentenced by a court in neighbouring Xinjiang late last month to 15 years for "grave-robbing".

"These sentences are causing fear among a lot of Tibetan intellectuals," Woeser told AFP while declining to comment further on the verdict due to concerns over possible government reprisals.

Karma Samdrup`s wife confirmed the sentence on her Twitter account.

Xia Jun, Rinchen`s lawyer, was unreachable Sunday by telephone, while phones at the Chamdo intermediate court went unanswered.

Chinese authorities have been accused of heavy handed measures against alleged "separatist" forces in the Himalayan regions since violent anti-Chinese riots erupted in Lhasa in April 2008 and spread to other parts of Tibetan inhabited regions.

Late last year, Chime Namgyal, Rinchen Samdrup`s younger brother, was sentenced to 21 months of "re-education through labour" for endangering state security, the London-based International Campaign For Tibet said in a statement on Saturday.

The two brothers ran the "Snowlands Great Rivers Environmental Protection Association".

"The case against Rinchen Samdrup is part of a larger case against his two brothers, two cousins, and other relatives and supporters and stands as a major case in which prominent Tibetans have been targeted and imprisoned despite no evidence of political activities," the statement said.

The brothers had previously been praised by Chinese authorities and the state media for their environmental work, it added.

According to Human Rights Watch, the brothers were arrested after attempting to highlight environmental abuses by local officials in Tibet.

The New York-based group has expressed concern over the "increasing vulnerability of important cultural and entrepreneurial Tibetan figures to politically motivated arrests and prosecutions".

BDST: 12:53 HRS, July 4, 2010