Shenzhou 6 is joined by Long March CZ-2F rocket at launch tower

China has launched its second manned space mission in what analysts see as a bid by the Communist government to boost its prestige.

Following a countdown, the Shenzhou 6 spacecraft lifted off from a desert in northwestern China's Gansu province on a mission that officials say may go for five days.

With President Hu Jintao watching from Beijing, astronauts Fei Junlong and Nie Haisheng started a journey that will have them orbiting 80 times around the world in their spacecraft, which is based largely on the design of the older Russian Soyuz models.

The launch reaffirms the Asian giant's place in space exploration. Only three nations have launched their own manned spacecraft. Chinese scientists conducted their first manned mission on October 23, 2003, when Colonel Yang Liwei circled the earth a few times - more than four decades after astronauts from the United States and the former Soviet Union had done so for the first time.

Observers see this as yet another effort by China's communist leaders to build their government's prestige. Independent space consultant James Oberg, a retired U.S. space engineer, says this and other launches will have a profound commercial and political value for the Chinese leadership.

"It enhances the value of every item of high technology that the Chinese intend to sell overseas," he explained. " It enhances the psychological value of every weapons system that China possesses or intends to sell overseas. And, it enhances every statement or promise and - I'm afraid to say - every threat that Chinese diplomats make overseas."

Chinese Prime Minister Wen Jiabao, speaking at the launch site Wednesday, said his country intends to use its space program for peaceful purposes - a bid to ease international concerns that have arisen over China's rapid military buildup.

"China's space flight scientific experiments stem completely from the objective of peace, and are also a contribution to mankind's scientific study and the cause of peace," he said.

Analysts say the Chinese leadership hopes the space program will enhance the government's image at home, where the Communist party is struggling to remain relevant at a time when China is becoming more of a free market economy and less of a socialist society.

The launch of the Shenzhou 6 and its two astronauts came the morning after Communist Party leaders wrapped up a meeting in which they laid out a five-year plan for the development of China's economy.