PARIS, March 5 (UPI) -- A foot patrol of France's entire system of train tracks did not turn up any bombs, as threatened by blackmailers, the International Herald Tribune said Friday.
Some 10,000 railway workers paired off and walked almost 20,000 miles of track Thursday in response to a series of bomb threats made an unknown group calling itself AZF.
The first threats arrived in letters sent to President Jacques Chirac and Interior Minister Nicolas Sarkozy beginning in December and continuing through Feb. 17.
The letters demanded more than $4 million, claiming that nine planted bombs could explode if the money was not paid.
Justice Minister Dominique Perben vowed Thursday the suspects would be captured rapidly.
"Certain details lead us to think we are dealing with people who are dangerous enough for us to take this matter very seriously," Perben said.
The Interior Ministry tried to keep the threats quiet to maintain contacts with the group, and issued a letter to reporters late Tuesday requesting no information be published "for evident reasons of security."