General Dynamics Corp. secretly has been helping the government of Taiwan develop a new fighter aircraft in Fort Worth for the past three years.

The aircraft is being designed by a group of about 100 Taiwanese engineers and technicians. GD employees are acting as "advisers" to the group but are not directly involved in the aircraft design or production, said a GD official associated with the program.

"We are not building it or designing it. We are merely teaching them how to design it," said the official, who spoke anonymously.

He said as many as several hundred GD employees work on the program. He said the project is worth about $200 million to GD, paid by the Taiwanese government. It also involves other U.S. contractors, he said.

The work is being done in a small, unmarked office building in Fort Worth. The building is surrounded by a barbed-wire fence, and entry is through a locked, remote-controlled gate.

According to the official, the program has State Department approval but has operated without publicity so as not to offend the People's Republic of China. Neither Taiwan nor mainland China officially recognizes the other.

The official policy of the U.S. government is not to sell or transfer advanced weapons systems or technology to Taiwan.

"It's a touchy political problem. The State Department knows about it, (mainland) China knows about it, but as long as it doesn't get a lot of publicity, they won't complain," the GD official said.

GD spokesman Z. Joe Thornton said Thursday that he could not comment on the program.

"We can't talk about that. . . . It's a sensitive issue," he said.