By Paul Eckert

BEIJING, Jan 19 (Reuter) - A western human rights group expressed concern on Friday that a six-year-old boy named by the exiled Dalai Lama as Tibetan Buddhism's second-ranking monk remains "missing" along with his family and other monks.

"Amnesty International is seriously concerned that a six-year-old Tibetan boy and his family have been missing from their home for eight months and may be under restriction by the authorities," the group said from its London headquarters.

Amnesty said a Tibetan abbot and more than 50 other monks and laypersons from the Himalayan region remained in detention in connection with a bitter dispute with China over the reincarnation of the Panchen Lama.

Chinese officials have steadfastly maintained that the boy is safe in Tibet but have declined to give further details.

Amnesty called on Beijing to disclose full details and lift any restrictions so the boy and his parents "are free to return to their village and live without restriction or harassment."

The Dalai Lama, Tibetan Buddhism's exiled god-king, last May identified Gedhun Choekyi Nyima, six, as the 11th Panchen Lama.

Beijing denounced the selection as invalid, saying the Dalai Lama's unilateral action violated a 200-year-old agreement under which China's government must approve all senior lamas.

Beijing enthroned its own "soul boy" choice, Gyaincain Norbu, also six, in November as the official reincarnation of the 10th Panchen Lama, who died in 1989.

State religious authorities reached by telephone in Tibet on Friday said they did not know the whereabouts of the boy named by the Dalai Lama or his family.

"We do not know if he is inside the country or abroad," a Religious Affairs Bureau official in Tibet's capital, Lhasa, told Reuters. "We have not been involved in his case."

The enthronement of a Communist Party-approved Panchen Lama caused a furore over the religious land Beijing has ruled, often with an iron fist, since China's 1949 communist takeover.

Amnesty International and Tibetan activists in exile have said Gedhun Choekyi Nyima and his family were taken to Beijing during the reincarnation row and not seen since. Amnesty said information received this month indicated no change.

Chinese authorities have declined to give details about the boy who the official Xinhua news agency has branded a dog-killer unfit for religious service.

"The boy is in sound health," Foreign Ministry spokesman Chen Jian said on Tuesday. "I stand by what I said."

Communist Party chief Jiang Zemin last week met China's official Panchen Lama in Beijing and urged the boy to defend patriotism -- something the boy agreed to do, according to official Chinese accounts.

China has portrayed the spiritual succession as part of an epic 30-year struggle with the Dalai Lama, condemned by Beijing as a pro-independent "splittist."

The Dalai Lama and thousands of followers fled to India in 1959 after an abortive anti-Chinese uprising, but he continues to command the loyalty of many Buddhists in Tibet.

The region has been rocked by often violent pro-independence protests since 1987. China has jailed many monks and nuns who have spearheaded the movement to separate Tibet from China.

REUTER