China is in effect holding two crew members of a hijacked Taiwanese airliner as hostages in an attempt to force Taiwan into negotiations on the incident, diplomats said here today.

The diplomats predicted that the maneuver would not work and that, if China persisted in holding the two men, it could turn a propaganda coup into a public relations fiasco.

The windfall came with the defection of a Taiwan-based China Airlines pilot, who flew his Boeing 747 cargo plane into the southern Chinese city of Guangzhou May 3. The pilot, Wang Xijue, asked to be reunited with family members living in China.

In the past, most defectors have headed in the other direction -- from China to Taiwan. The other two crew members, copilot Dong Guangxing and mechanic Qiu Mingzhi, made clear that they wanted to return to Taiwan.

On May 3, China asked the Taiwanese airline to send a representative to Peking as soon as possible to discuss with China's national airline how to deal with the plane, cargo, and two crew members who do not wish to stay.

Taiwan has rejected the idea of sending an airline representative to Peking. It tried to get the Hong Kong-based Cathay Pacific Airways to act as an intermediary. Yesterday, China renewed the call but offered to meet elsewhere. "I don't think they can force Taiwan into this," said an Asian diplomat here. "I think they'll have to back down."

But a western diplomat said, "I wouldn't rule out some kind of solution just yet . . . but there is pressure on Peking. The longer they don't do anything with those two crew members, the more it looks like they're holding those two men as hostages. "They don't want to be accused of treating their brothers from Taiwan cruelly at a time when they want to be demonstrating flexibility to Taiwan."

China regards Taiwan as a breakaway province and has been trying for years to get it to engage in talks aimed at unification. But Taiwan has refused. Peking has proposed a "one country, two systems" formula under which Taiwan would maintain its own system of government and its army even after reuniting.

Some officials in Peking have indicated that they would feel more comfortable negotiating with the aging leader of Taiwan, Chiang Ching-kuo, who is from the mainland, than they would with possible successors to Chiang.