A senior U.S. administration official said Thursday that allegations of illegal CIA activities in Europe were hurting intelligence cooperation between the United States and European governments.

John Bellinger, Legal Adviser to the U.S. Secretary of State, spoke as the European Parliament and the continent's leading human rights body were investigating reports that the CIA operated secret detention centers and flights in Europe, some of them carrying terror suspects to countries where they could face torture.

"This furor over renditions, and the furor over the flights alone, and the suggestion that flights alone are somehow improper ... already is undermining intelligence cooperation," Bellinger told reporters in Brussels, where he was meeting EU and NATO officials.

"Next time, the U.S. may be reluctant to bring people to Europe or exchange information," he added.

Bellinger did not deny there have been CIA flights over Europe or ones with stopovers, but he dismissed implications that they all had detainees on board. He said the flights may have carried intelligence experts, counterterrorist officials or forensic evidence.

"There have been very few cases of renditions ... the suggestion that there has been a large number of flights is simply an absurd allegation," he said.

Asked whether the secret handing over of terror suspects to U.S. agents continued, Bellinger said he "would not assume that at all."

"The last allegation of rendition was something like three years ago."

EU lawmakers said last week that data from the EU's air traffic agency show there have been over 1,000 clandestine CIA flights over European territory since the Sept. 11, 2001, attacks on the United States. But they said it was not clear if detainees were on board.

A European Parliament delegation is traveling to Washington next week to meet U.S. Assistant Secretary of State Daniel Fried and other officials.

The allegations that the CIA hid and interrogated key Al Qaeda suspects at Soviet-era compounds in Eastern Europe were first reported last year. Human Rights Watch identified Romania and Poland as possible sites of the detention centers, but both countries denied involvement.

The EU parliament launched an inquiry into the reports in January, and has so far heard from senior EU officials, human rights activists and people who said they were kidnapped by U.S. agents and transferred to secret prisons. Lawmakers said Thursday they would also seek a meeting with NATO Secretary General Jaap de Hoop Scheffer.

No senior EU official or government leader has confirmed any questionable or illegal CIA activities on European territory.

Italian Socialist deputy Giovanni Claudio Fava, a member of the inquiry committee, said the EU Parliament will not stop its inquiry, despite Bellinger's remarks.

"I don't accept that. Our job is to find out the truth, and if the truth is that there have been illegal CIA flights on our territory we can't remain silent. Our job of defending human rights and the rule of law is important," Fava said.

In March, the parliament heard testimony from Kuwaiti-born German citizen Khalid al-Masri, who said he was detained by foreign agents in Macedonia on Dec. 31, 2003 while on holiday. He said he was held and interrogated in a hotel in Skopje until Jan. 23 the following year and flown to Afghanistan, where he said he was tortured before being flown back to Europe and released in Albania five months later.

The lawmakers — who were in Skopje last week to discuss al-Masri's allegations with Macedonian officials — said records obtained from the EU's air traffic agency indicate there was a CIA-operated flight from Skopje to Kabul via Baghdad overnight from Jan. 23-24, 2004.

They said Macedonian officials for the first time confirmed that al-Masri stayed in an expensive hotel in Skopje for 23 days, but denied he was interrogated by CIA agents and insisted he left the country overland for Kosovo.

"But we were not allowed to see documentation proving he did leave overland. There is some need to find out what went on during those 23 days," said Italian Socialist deputy Giovanni Claudio Fava.

Also in March, the lawmakers heard from Syrian-born Canadian citizen Maher Arar, who said he was detained in New York in 2002 while returning from vacation and flown via Rome to Syria, where he was allegedly kept in a secret prison.