THE HAGUE, Netherlands (AP) — European Union police agency Europol on Wednesday blamed human error for a breach of its data security rules by a former staff member that reportedly led to dossiers containing information about terrorism investigations becoming visible online.

Dutch investigative television show Zembla reported that a Europol staffer — in a breach of the agency's tight security rules — took dossiers home and copied them to a backup drive that was linked to the internet.

The breach could undermine faith in the organization among EU member states that share highly sensitive intelligence with Europol as a way of boosting continentwide investigations into terrorism and organized crime.

"This leak damages trust in Europol and trust in information exchange, which is our top priority in the security agenda," said Sophie in 't Veld of the ALDE liberal group in the European Parliament. "Information sharing is essential for security."

The liberal bloc called on Europol Director Rob Wainwright and European Commissioner Julian King, whose portfolio includes security, to explain the situation to the European Parliament.

In a statement, Europol sought to allay concerns, saying that the organization "adheres to the highest standards of data security, including continuous security briefings provided to staff members."

But it conceded that "human error is the weakest link when it comes to the intersection of staff, data, and technology."

Zembla said it found more than 700 pages of confidential police dossiers that mention European terrorism investigations on the drive, including the names and phone numbers of people linked to terror investigations. Among the investigations mentioned was the probe into the deadly Madrid train bombings in 2004 that killed 191 people.

Europol said the breach related to "sensitive information dating from around 10 years ago."

The Hague-based organization added that it is investigating the breach and had immediately informed member states involved in the investigations.

"As of today, there is no indication that an investigation has been jeopardized, due to the compromise of this historical data," the organization said in a statement. "Europol will continue to assess the impact of the data in question, together with concerned member states."

Associated Press writer Raf Casert in Brussels contributed to this report.