Brother helps ETA 'terrorist' flee

ETA's campaign for a Basque state has claimed 800 lives since 1968

PARIS, France -- French prison officials have started an investigation into how a suspected Basque terrorist escaped from a top-security jail in the French capital by swapping places with his brother during a visit.

The switch at Sante prison took place on Saturday but was only discovered on Thursday, prison officials said.

The escapee, Ismael Berasategui Escudero, is a suspected member of the Basque separatist movement ETA. He was arrested on May 14 in southern France. The brother who took his place in prison was held on Thursday for questioning and could face charges of aiding an escape. His name was not revealed.

"There is a natural physical resemblance between the two men, which was reinforced by their thought-out desire to slip our guard," the prison director, Alain Jego, told The Associated Press. "It's hard to tell them part."

Investigators suspect ETA may be responsible for the escape. Each Sante inmate receives three visits a week. Their hands

EXTRA INFORMATION In-depth: Basque conflict

are stamped with invisible ink before entering the visiting room. After the visit, guards check the ink is still there and that visitors have none on them.

Spanish authorities suspect Berasategui of belonging to an ETA cell broken up in December 2001, when he went on the run. Spanish investigators allegedly found three loaded pistols, 130 pounds of explosives and bomb manuals in his apartment.

Ahead of a trial, French authorities were holding him on charges of "criminal conspiracy related to a terrorist enterprise," carrying weapons and receiving stolen goods.

ETA has claimed responsibility for more than 800 deaths as part of a 34-year drive to create an independent Basque homeland in northern Spain and southwest France.

Spain, the European Union and the United States consider it a terrorist group.

Copyright 2002 CNN. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed. Associated Press contributed to this report.