A legislative panel is to urge the government on Friday to properly investigate claims that British airports were used by planes ferrying terror suspects to secret detention centers in Europe.

The Joint Committee on Human Rights is to say ministers have not shown that they fully investigated claims that the U.S. Central Intelligence Agency was secretly moving terror suspects around Europe in "ghost flights," a practice known as extraordinary rendition.

According to a report to be issued by the committee, the government "should take active steps to ascertain more details about certain flights known to have used U.K. airports and suspected of involvement in extraordinary renditions."

Allegations that CIA agents shipped prisoners through European airports to secret detention centers, including compounds in eastern Europe, first surfaced in U.S. media reports late last year.

Clandestine prisons and secret flights through or from Europe to countries where suspects could face torture would breach Europe's human rights conventions.

A European Parliament committee is inquiring into the allegations. Data from the EU's air traffic agency show there have been more than 1,000 suspected clandestine CIA flights stopping on European territory since the Sept. 11 attacks in the United States in 2001.

Speaking in Brussels, Belgium, earlier this month, John Bellinger, legal adviser to U.S. Secretary of State Condoleezza Rice, did not deny there have been CIA flights stopping in or flying over Europe, but he dismissed implications that they all carried detainees.

He said the flights may have carried intelligence experts, counterterrorism officials or forensic evidence.

The Committee on Human Rights report will say that if any of the civil aircraft previously alleged to have been used in extraordinary renditions should return to Britain, they should be required to land and should be boarded and searched by police.

The identity of everyone on board should be verified, it adds, and "wherever appropriate, a criminal investigation should be initiated."

The committee is also to note that chartered civil aircraft passing through Britain currently do not have to provide passenger lists, and will urge ministers to require that information.

The report will also criticize the British government for seeking memoranda of understanding with countries including Libya, Lebanon and Jordan that they would not torture anyone extradited there from Britain.

This "could place deported individuals at real risk of torture or inhuman and degrading treatment, without any reliable means of redress," the report says.