A copy of letter written by the 14th Dalai Lama to Chairman Mao in October 1951, the year marks the peaceful liberation of Tibet, has been now declassified to the public by the State Archive Administration, the China Daily reported in Beijing on Wednesday.

About 40 percent of the documents held by the State Archive Administration have been opened up to public scrutiny, Yang Dongquan, head of the administration said.

In the letter, the 14th Dalai Lama said that "the local government of Tibet as well as the Tibetan monks and laymen unanimously support this agreement, and will actively assist the People's Liberation Army in Tibet to consolidate national defense, drive imperialist forces out of Tibet and safeguard the unification of the territory and the sovereignty of the motherland."

According to Yang, the materials are useful in recording real history, safeguarding the unification of the territory and informing younger generations.

"In March, 2008, we put on five videos themed on the truth of Tibet on our official website in order to correct people's false and prejudice toward Tibet. The videos were made based on a series of archives kept in our administration including appointing and dismissing officials in Tibet by generations of Chinese Central Government, conferring the titles of the Dalai Lamas and the slave trade before the democratic reform of Tibet," said Yang.

"The videos were reprinted by around 400 websites at home and abroad in both Chinese and English,” he added.

People wanting to look at documents need to show their identification cards and research achievements in a related field along with letters of introduction from their employers if they want to see the declassified materials.

The State Achieves Administration, which was founded in 1954, is responsible for collecting, arranging, preserving and providing access to documents with long-term values.