BEIJING, Dec 29 (Reuter) - A bomb has exploded outside a government office in Lhasa, the capital of China's restive Himalayan region of Tibet, and local authorities have described the act as "an appalling act of terrorism," radio reports said.

The bomb exploded on the doorstep of the Lhasa City Chengguan District Government Office early on December 25, local radio reported on Friday, quoting a circular issued by the regional Communist Party committee and government.

"The bombing... was an organised, planned, and targeted counterrevolutionary bombing incident staged by the Dalai (Lama) clique," the circular said according to the radio report, monitored by the British Broadcasting Corp and made available early on Sunday.

It was "a serious counterrevolutionary political incident and an appalling act of terrorism," the radio said.

The report did not say whether the blast caused any casualties or damage.

However, the London-based Tibet Information Network (TIN) said five people were reported to have been wounded in the blast, some seriously. They included two nightwatchmen at the district government office and shopkeepers living nearby.

Almost all windows within a 100-metre (yard) radius of the blast near the city centre were shattered and a nearby branch of the Bank of China was also reported to have been badly damaged, TIN said.

"The act of terrorism staged by the Dalai (Lama) clique is opposed by the people of Lhasa City, as well as by people all over the world," the party circular said.

China regularly blames followers of Tibet's exiled god-king, the Dalai Lama, for anti-Chinese unrest that erupts sporadically in the strategic mountainous region that straddles the Himalayas and runs along China's sensitive border with India.

Speaking at a meeting of party officials in Lhasa on Friday, the vice chairman of the autonomous regional government, Gyamco, said efforts should be made to counter such attacks.

"We should wage a tit-for-tat struggle against the Dalai clique's sabotage," he said.

"We should, once again, stage another campaign across Tibet to thoroughly expose and criticise the Dalai clique, heighten our alertness and strengthen preventive measures so as to keep the situation stable," the radio quoted him as saying.

The Dalai Lama fled his Himalayan homeland in 1959 after a failed uprising against communist rule and won the Nobel Peace Prize 30 years later for his non-violent campaign for autonomy for Tibet.