Thousands of police and rail workers have combed the French railway network in a fruitless search for bombs as anger mounted over the delay in publicizing an extortion plot.  

The threats by a previously unknown group were first sent to the offices of French President Jacques Chirac and Interior Minister Nicolas Sarkozy in December and then again in February; they were only made public Wednesday.

AZF claimed to have planted 10 bombs under rails in the French rail system and demanded a ransom of more than US$4 million.

Last month the group directed government officials to a bomb that was packed in a plastic container hidden under rail lines in central France.

The revelation sparked anger among commuters Thursday. "Once more, the law of silence has prevailed," the Federation of Transport Users said in a statement.

"The French people should have been informed of the threat, which was known and being taken seriously," the statement said. "It was up to them and them alone to decide ... whether or not to take the train while the network was not safe."

Officials had earlier asked for a media blackout to avoid jeopardizing efforts to contact the group. But the Interior Ministry released details Wednesday after the story leaked out.

Thursday's newspapers were devoted to the issue. "Who's blackmailing the state," asked Le Figaro, while the banner headline in Liberation newspaper read: "Blackmail on the tracks."

Meanwhile, fearing more bombs could be hidden, the state rail company SNCF sent nearly 10,000 maintenance workers to inspect its 32,000 km (20,000 miles) of track on foot; they found nothing.

The group directed police to one bomb under tracks near Limoges.

SNCF, the French national railway system, said nothing was found but added inspections would continue because of the threats. Security on the network was heightened, but services were normal, The Associated Press reported.

"If I felt that security wasn't assured, we wouldn't run trains," AP quoted SNCF Chairman Louis Gallois as saying.

Police said the train station in Grenoble, at the foot of the French Alps and busy with skiers, was evacuated for more than an hour Wednesday after authorities received a threat from a person identifying himself as a member of AZF, AP reported. No bomb was found.

AZF is an apparent reference to the name of a chemical factory in southwestern France that exploded in 2001, killing 30 people. Investigators believe the 2001 AZF explosion was accidental, The Associated Press said.

Europe 1 radio said the group described itself as "secular terrorists" but that police thought they were criminals trying to blackmail SNCF, Reuters reported.

Internationally renowned anti-terror judge Jean-Louis Bruguiere has taken over the investigation, AP quoted LCI as reporting.

(China Daily March 5, 2004)