The United States has told the European Union it needs more time to respond to media reports that the CIA set up secret jails in some European nations and transported terror suspects by covert flights, the top EU justice official said Monday.

Justice and Home Affairs Commissioner Franco Frattini also warned that that any of the 25 bloc nations found to have operated secret CIA prisons could have their EU voting rights suspended.

The Council of Europe — the continent's main human rights watchdog — is investigating the allegations, and EU justice official Jonathan Faul last week formally raised the issue with White House and U.S. State Department representatives, Frattini said.

"They told him, 'give us the appropriate time to evaluate the situation.' Right now, there is no response," he said.

The CIA has refused to comment on the European investigation.

Frattini said suspending EU voting rights would be justified under the EU treaty, which stipulates that the bloc is founded on the principles of liberty, democracy, respect for human rights, fundamental freedoms and the rule of law, and that a persistent breach of these principles can be punished.

Clandestine detention centers would violate the European Convention on Human Rights.

Allegations that the CIA hid and interrogated key Al Qaeda suspects at Soviet-era compounds in Eastern Europe were first reported Nov. 2 in The Washington Post. A day after the report appeared, Human Rights Watch said it had evidence indicating the CIA transported suspected terrorists captured in Afghanistan to Poland and Romania.

Frattini said Romania's interior minister, Vasile Blaga, had assured him the allegations were untrue and that a base at Mihail Kogalniceanu — used by American forces from 2001-03 to transport troops and equipment to Afghanistan and Iraq — was not used as a detention center.

"It is very, very important to get the truth. It is impossible to move only on the basis of allegations," Frattini said.

Reports of secret CIA flights followed the allegations of secret prisons, as more and more countries have decided to open investigations into the issue. Frattini said if the flights took place without the knowledge of local authorities, they would be violations of international aviation agreements.

Other airports that might have been used by CIA aircraft in some capacity include Palma de Mallorca in Spain, Larnaca in Cyprus and Shannon in Ireland, as well as the U.S. air base at Ramstein, Germany, EU officials have said. Investigations into alleged CIA landings or fly overs have been launched in Austria, Denmark, Iceland, Norway and Sweden, and there have been unconfirmed reports in Macedonia and Malta.