PARIS — Preliminary evidence suggests that American agents kidnapped people in European countries, held them there temporarily and illegally transferred them across the countries' borders, a European investigator said on Tuesday.

The investigator, Dick Marty, said he believed that the United States was no longer holding detainees in Europe, having transferred them to North Africa in early November, after The Washington Post reported that the CIA maintained prisons in at least eight countries, including some in Eastern Europe.

Marty is investigating those reports and whether European governments had turned a blind eye to U.S. breaches of European rules on human rights. He stressed the preliminary nature of his report. According to the statement released Tuesday, it is based primarily on published information, ongoing legal proceedings, talks with some of the nongovernmental organizations and individuals involved and discussions with journalists.

Marty sharply criticized the United States as failing to give a full accounting of its actions, notably during Secretary of State Condoleezza Rice's visit to Europe last week. But he also said he believed that there was some degree of collaboration from European officials.

Human Rights Watch has identified Poland as the site of the CIA's main base for holding and interrogating terrorist suspects and has said that Romania was a key transit point for detainees. Both countries have denied the charges.

Washington and a number of European capitals have also come under pressure to account for dozens of CIA flights on the continent, some of which are thought to have transported suspects to countries with a track record of torture and cruel treatment.

During her visit last week, Rice acknowledged that the United States had moved terrorist suspects to third countries to be "questioned, held or brought to justice." But she said that American agents had acted only with the permission of the government of the country where the suspect was captured. She also said that all American personnel — including those of the CIA — were subject to the United Nations Convention Against Torture.