Tourists and space enthusiasts were thronging into Jiuquan city in the vast deserts of northwest China Thursday, keenly anticipating the launch of the nation's third manned space flight.

Eager Chinese from Vice President Xi Jinping on down were expected in the remote area for the evening launch of Shenzhou VII, which would carry three astronauts on the nation's most ambitious journey into space yet.

"Certainly we're excited," Wang Ling, a manager at the Jingdian tourist agency, told AFP.

"Everyone here knows people who work up at the launch centre, so many want to go watch it."

Special guests of the defence ministry and China's numerous space agencies have packed Jiuquan hotels, and from early morning they started crowding into buses to travel the 280 kilometres (170 miles) to the launch site.

Security was tight along the two-lane highway which cuts through vast expanses of barren desert and provides a thin lifeline between the Jiuquan Satellite Launch Centre and the outside world.

Uniformed police and the occasional submachine-armed member of the People's Liberation Army kept a watchful eye on traffic toward the secretive centre.

At one roadblock, police officers inside a tent checked the identification of drivers and passengers on laptop computers, ensuring they were among those invited.

"Ordinary Chinese can go watch the flight, but they must get approval by the State Security Ministry and be issued a pass to get on the launch site," said Zhu Xiaoling, an agent at the Shenzhou Tourist Agency.

"Only a few travel agencies have been given a quota on the number of tourists they can bring. The process is very restricted."

At the Jiuquan train station, a steady stream of tourists aiming to catch a glimpse of the launch arrived in the days before the launch, and while many had no pass to go the site, they remained hopeful.

"My company sent some people to watch the launch of the Chang'e (lunar explorer) earlier this year," said Gao Lilin, a computer programmer from northwest China's Shaanxi province.

"Now it's my turn to witness history."

Tickets to the event cost 1,500 yuan (220 dollars), just under a monthly wage for an ordinary Chinese.

Much of the ongoing barrage of publicity for the flight is aimed at further showcasing China's rising political and economic might following the successful hosting of the Beijing Olympics last month.

China's communist-led government is also keen on better publicising the nation's drive to embrace science and technology.

For China's second manned space flight, Shenzhou VI, in October 2005, Prime Minister Wen Jiabao witnessed the launch in person.

This time the most important VIP would be Vice President Xi, widely seen as a top candidate to become China's leader when power shifts hands in four year's time.

Xi would shake hands with the three astronauts hours before their launch, meeting them outside their apartment compound, called Wentiange, or "Ask the Sky," the China Daily newspaper reported.