Speaking in Shanghai toward the end of the first visit to China by top officials from the National Aeronautics and Space Administration, Mr. Griffin said there were "no current plans to work with China on the space shuttle and space station programs."

Mr. Griffin, who characterized the five-day visit as enjoyable and informative, said that it was too early to talk about any cooperative programs between the nations, but that the first steps probably would be in data sharing and some type of joint effort with robotic spacecraft.

"We did discuss closer cooperation in our nations' science programs," Mr. Griffin said during a news conference in which American reporters participated by telephone. "We're all very encouraged by those initial discussions."

Mr. Griffin said earlier that the International Space Station program involving the United States and 15 other nations had well-established partnerships after almost 13 years and that he would not propose changing it. And since the space shuttle program is to close down in 2010 with the retirement of the three remaining orbiters, there is little prospect of Chinese involvement, he said.

China, only the third nation, after Russia and the United States, with the capacity to send humans into space, has been seeking more international cooperation in space projects, but Washington has been reluctant because of such issues as technology transfer, trading weapons technology and human rights.

The biggest difficulty, Mr. Griffin said, was with a civilian agency like NASA working with a Chinese space program dominated by that country's military. Aside from concerns about national security issues, like missile technology proliferation, human space cooperation "requires a great deal of trust and openness."

Partners in human space flight have to understand one another's equipment, systems and procedures completely, as the United States and Russia have learned to do, he said.

"We have to have a great degree of trust. If not, there is a real danger in the mix," Mr. Griffin said. "If we're going to fly together, we're going to have to depend on each other."

Mr. Griffin said the NASA group chose not to visit the Jiuquan Satellite Launch Center, an extensive rocket-launching complex in the Gobi Desert from which the Chinese prepare and fly their manned spacecraft and keep an extensive inventory of rockets.

NASA officials had received permission to visit the base, which is operated by the People¡¯s Liberation Army. But they were told that the tour would be limited to the launching pads and that they would not have access to the buildings where spacecraft are tested and prepared for launching. Mr. Griffin said that if he had been allowed to see the engineering facilities and have "eye-level discussions" with fellow engineers, he would have gone.

"I am not a tourist; this is, in fact, my profession," Mr. Griffin said at the news conference. "I have seen a lot of launch pads in my time and didn't need to go that far to see another one."

Mr. Griffin said his "get acquainted" visit, during which he met Chinese space officials and toured a number of science centers, had generally been "very enjoyable" and informative.

"Our hosts could hardly have been nicer," he said. "This is our very first visit. It¡¯s not our last visit."