XinhuaNet, the Web site of the government's official news agency, said in a brief dispatch that the trio of finalists had arrived at northwestern China's Jiuquan Satellite Launch Center, where security is tight. Xinhua cited "informed sources."
It said the "No. 1 astronaut" among them would make the flight — the firmest indication yet that the Shenzhou 5 capsule will carry only one passenger.
China has scheduled its landmark first manned spaceflight for sometime between Wednesday and Friday, though many state-controlled newspapers have said it would be Wednesday. The craft is expected to orbit the Earth 14 times before returning.
A successful trip would make China the planet's third spacefaring nation, after the former Soviet Union and the United States.
The Xinhua report said the three finalists arrived at Jiuquan on Sunday, the day the space center was featured in Chinese media. Xinhua said they were to undergo final testing Tuesday to determine who makes the flight.
The Shenzhou is based on the three-seat Russian Soyuz capsule, which had prompted suggestions that China might send up as many as three astronauts. But outside experts and Chinese news reports say the first flight is likely to carry only one.
State media said Monday that the rocket is waiting on its launch pad.
Chinese media stepped up publicity for the flight planned later this week, filling newspapers and Web sites with pictures of the launch base and student model-rocket builders.
The flight will be a prize of propaganda and prestige for which the communist government has invested 11 years of planning, billions of dollars and untold resources.
After months of official silence, the government confirmed Friday that it would make the flight and that the capsule would circle the planet 14 times.
During the weekend, state media started churning out publicity that included descriptions of the launch pad and surrounding town in the Gobi Desert, a former oasis stop on the ancient Silk Road whose status as a space center was once a closely guarded secret.
A photo by the official Xinhua News Agency used Monday by newspapers and Web sites showed what Xinhua said was the Long March rocket for the flight on its pad in Jiuquan. The rocket itself wasn't visible behind the launch tower. The Long March refers to Mao Tse Tung's successful campaign to bring a communist government to China.
A two-sentence caption said the base was "quietly awaiting" the launch but gave no other information.
As the hours counted down to the history-making launch, the government maintained its secrecy about who among its first corps of 14 astronauts — all of them fighter pilots whose names haven't been released — would make the trip.
The Xinhua report on the selection of astronauts, citing only "informed sources," said the three finalists arrived at Jiuquan on Sunday. It said they were to undergo final testing Tuesday to determine who makes the flight.
Also Monday, photos in Beijing newspapers showed teenagers launching model rockets at a weekend event to mark the Chinese capital's 21st annual Junior High School Students Love Science Month.
The coverage is a sharp departure for the secretive, military-linked program, whose silence forced Chinese newspapers to pass along unconfirmed, sometimes conflicting reports.
The outpouring of information fueled the enthusiasm of China's public for the launch and its pioneering, though still anonymous, pilot.
"Of course he'll be a hero. He'll be as famous as Lei Feng," said Luo Yongjun, a Beijing resident, referring to a Chinese soldier who was lionized by the Communist Party's propaganda machine in the 1960s as a model of selfless revolutionary virtue.
By Joe McDonald