WASHINGTON - Multiple congressional computers have been hacked by people working from inside China, two lawmakers said yesterday, suggesting the Chinese were seeking lists of dissidents.

Two House members, both critics of Beijing's human-rights record, said the compromised computers contained information about political dissidents from around the world.

Rep. Frank R. Wolf (R., Va.) said four of his computers were compromised, beginning in 2006. New Jersey Rep. Christopher H. Smith, a senior Republican on the House Foreign Affairs Committee, said two of his computers were attacked, in December 2006 and March 2007.

Wolf said that after one of the attacks, a car with license plates belonging to Chinese officials went to the home of a dissident in Fairfax County, Va., outside Washington and photographed it.

During the same time period, the House International Relations Committee (now known as Foreign Affairs) was targeted at least once by someone working inside China, committee spokeswoman Lynne Weil said.

Yesterday's disclosures came as U.S. authorities investigated whether Chinese officials secretly copied the contents of a U.S. laptop computer during a visit to China by Commerce Secretary Carlos M. Gutierrez and used the information to try to hack into Commerce Department computers.

Wolf said the FBI had told him that computers of other House members and at least one House committee had been accessed by sources working from inside China. He suggested that Senate computers could have been attacked as well.

Wolf said that the hacking of computers in his Capitol Hill office began in August 2006, that he had known about it for a long time, and that he had been discouraged from disclosing it by people in the U.S. government he would not identify.

"The problem has been that no one wants to talk about this issue," he said. "Every time I've started to do something, I've been told: 'You can't do this.' A lot of people have made it very, very difficult."

The FBI and the White House declined to comment. The Bush administration has been reluctant to discuss or acknowledge cyber attacks, especially ones traced to China.

In the Senate, the office of Richard J. Durbin (D., Ill.), who chairs the Senate's subcommittee on humanitarian issues, asked the sergeant at arms to investigate whether Senate computers have been compromised.

Wolf said that the first computer hacked in his office belonged to the staffer who works on human-rights cases and that others included the machines of Wolf's chief of staff and legislative director. "They knew which ones to get," said Dan Scandling, who is on leave as the chief of staff.

Smith said the attacks on his office computers were "very much an orchestrated effort." After the first intrusion, in December 2006, "that was the last time" his office put dissidents' names on its computers, Smith said.

He said the intrusions were discovered when House technicians found a virus that seemed designed to take control of the computers.

In Beijing, the Chinese Ministry of Foreign Affairs had no immediate comment on the allegations by Wolf and Smith.