The European Union's top justice official said Tuesday that suspected terrorists had been transferred to U.S. intelligence agents on European territory, but he added that it was not known whether these actions were illegal.

EU Justice and Home Affairs Commissioner Franco Frattini called for thorough national investigations into all reports of questionable activities by foreign intelligence agents and Europe's collusion in possible human rights violations.

Frattini spoke after Europe's leading human rights watchdog, the Council of Europe, voted to continue its inquiry into alleged CIA secret flights and prisons in Europe and called for safeguards to prevent human rights abuses by foreign intelligence agents.

The council vote also endorsed the findings of a seven-month investigation by Swiss Sen. Dick Marty, who earlier this month reported circumstantial evidence of several renditions on European territory.

Frattini acknowledged it as a "fact" that such incidents occurred on European territory since the Sept. 11, 2001, attacks on the United States, but said it was not clear whether governments were aware of them or cooperated, and it was similarly unclear whether the renditions were legal.

He said it was up to national authorities to investigate all reports of questionable CIA activities on their territory. Only then would the EU be able to take action, should collusion or breaches of international human rights standards by EU member states be proven, he said.

"It's extremely premature to draw consequences from the elements so far available. What we must do is make sure that national authorities understand that they have not only the power but the duty to carry out judicial investigations," Frattini said.

"They have the duty to establish national committees. I am determined to encourage, to put political pressure if necessary, on the home affairs ministers so that we get results (of the inquiries). Once you have a court decision only than you can claim you had a valid piece of evidence," he said.

In his report, Marty alleged European nations aided the movement of 17 detainees who said they had been abducted by U.S. agents and secretly transferred to detention centers around the world. Some said they were transferred to the U.S. detention facility at Guantanamo Bay, Cuba, and others to alleged secret facilities in countries including Poland, Romania, Egypt and Jordan. Some said they were mistreated or tortured.

"Marty's report showed facts. Several such facts did happen. ... It's impossible to draw legal judgments. Now it's up to national authorities to draw conclusions," Frattini said.

Bosnia has acknowledged handing six Algerian terror suspects over to U.S. authorities in 2002, ignoring a ruling by the country's highest court ordering their release. All six — five of whom had Bosnian citizenship — ended up at the Guantanamo facility.

Sweden let U.S. agents handle the extradition of two Egyptian terror suspects in 2001. Lawmakers and human rights groups harshly criticized Sweden for letting the suspects be sent back to Egypt, where they were imprisoned on terrorism charges.

Macedonia and Germany have denied any wrongdoing in connection with the alleged abduction of a German national by U.S. intelligence agents to a secret prison in Afghanistan in 2003. German lawmakers questioned Lebanese-born Khaled al-Masri about the case on June 22.

Frattini said it was vital for European countries to clearly define the powers of secret services. He also called for clarification of international air traffic rules to ensure that no aircraft used in military, customs or police operations avoids the obligation to obtain special authorization to land.

The European Parliament has accused EU member states of breaching an international treaty governing air traffic regulations by allowing secret CIA flights with a police mission to land freely on European territory.

In his report, Marty provided no direct evidence, but alleged that most European governments did not seem eager to help him establish the facts. He relied mostly on flight logs provided by the European Union's air traffic agency, statements gathered from people who said they had been abducted by U.S. intelligence agents, and judicial and parliamentary inquiries in various countries.

He concluded that several countries let the CIA abduct their residents, while others allowed it to use their airspace or turned a blind eye to questionable foreign intelligence activities on their soil.