NEW DELHI, Dec 30 (Reuter) - Tibet's government-in-exile said on Monday that last week's bomb blast in Lhasa could have been carried out by China as an excuse to increase repression in their Himalayan homeland.

China has launched a manhunt across the restive mountainous region after a bomb blast on Christmas Day outside city government offices in the Tibetan capital.

"We suspect that the bombing may have been carried out by the Chinese authorities themselves," said a statement by the exiled government, headquartered in India's Himalayan foothills.

Chinese officials said there was little doubt the blast was politically motivated and carried out by followers of the Dalai Lama, Tibet's exiled spiritual leader, and regional officials have threatened reprisals.

"Even if the detonation has been carried out by Tibetans it is a spontaneous expression of the widespread sense of frustration and desperation in Tibet with the increasing Chinese government repression," said the statement quoting Kalon Tashi Wangdi, the information minister.

The statement was issued from Dharamsala, in India's northern state of Himachal Pradesh, where Tibet's government-in-exile has been located since the Dalai Lama fled there in 1959 after an anti-Chinese uprising failed.

Wangdi said the Chinese rulers may have ordered the bombing to divert domestic attention from internal problems as well as to justify increasing repression in Tibet to the outside world.

"The Chinese government has everything to gain from an incident like this," the minister said.

China has already launched a crackdown on all Buddhist monasteries, banned photographs of the Dalai Lama and imposed a Chinese substitute on the Tibetan people, the statement said.

"We are concerned that the Chinese authorities may use the latest incident of (a) bomb blast in Lhasa as a pretext for increasing political repression in Tibet."

Wangdi denied that Tibet's exiled leaders were responsible for the attack.

"We would like to categorically point out that Dharamsala has absolutely nothing to do with this bomb blast or all the previous blasts which the Chinese authorities have accused us of," the minister said.

Chinese officials have said that no one was injured by the Christmas Day blast but the statement from Dharamsala put the number of casualties at five.

"We are sad that five people have been injured," the information minister said.

"His Holiness the Dalai Lama has publicly stated on numerous occasions that he would abdicate his leadership of the Tibetan people if the Tibetan freedom struggle turns violent," he said.

Wangdi said the exiled government opposed violence and has renounced it as national policy and remained committed to a negotiated political settlement.

Lama, who won the Nobel Peace Prize in 1989 for his non-violent campaign to win autonomy for his homeland, says he wants self-government and freedom of worship in the deeply religious Buddhist region.

Several much smaller bombs have been been set off in Lhasa in the last two years, including one in 1995 that caused slight damage to a plaque donated by Beijing and another last March outside the headquarters of the Tibet regional government.