UPDATE 2-Paris police find explosives and guns in Islamist probe

* Components of improvised explosives found in garage

* Incident revives fears of France's large Jewish community

* Security to be boosted at synagogues

(Edits, adding context)

PARIS, Oct 10 (Reuters) - French authorities said on

Wednesday they had rooted out an "extremely dangerous terror

network" after uncovering weapons and bomb-making materials in

their investigation of suspected radical Islamists detained at

the weekend.

Paris prosecutor Francois Molins said a dozen people

arrested on Saturday would be held for a further 24 hours after

chemicals used to make explosives were found at a garage in the

Paris suburbs belonging to one of them.

The raids were triggered by a grenade attack on a kosher

grocery store outside Paris last month, and have further

unsettled Europe's largest Jewish community, which was shaken

when an al Qaeda-inspired gunman shot dead three Jewish children

and a rabbi in Toulouse in March.

"We are clearly confronted with an extremely dangerous

terror network," Molins said in a statement to the media. "It is

essential to extend their stay in custody."

Investigators carried out overnight searches of garages in

Torcy, a town in the eastern suburbs of Paris, after Saturday's

raid ended with police shooting dead an Islamist suspect linked

to the grenade attack and arresting 11 others.

Another suspect was subsequently arrested, bringing the

total to 12.

Police on Saturday found a list of local Jewish groups at

the home of one of the suspects. Molins said a search of the

suspect's garage had revealed a shotgun, a revolver, bags of

potassium nitrate, sulphur and a pressure cooker.

"These are all products used to make what we call improvised

explosives," he said.

JEWS ON EDGE

While Britain and Spain have suffered coordinated Islamist

militant attacks on their capitals in the last 10 years, France

had not seen an attack with mass casualties on its soil since

1995, when an Algerian Islamist group bombed the underground

Metro network and other sites in the capital.

Molins said the detention of the dozen suspects could be

extended by a further six days if necessary.

France's Jewish community has been on edge after a series of

attacks in recent months. In the worst incident, 23-year-old

Mohamed Merah, seemingly acting alone, killed three soldiers in

two separate attacks before shooting dead three children and a

rabbi outside a Jewish school in Toulouse.

Interior Minister Manuel Valls said there were several

hundred radical Islamists in France capable of acts of

terrorism, and that its prisons were breeding radicalism.

President Francois Hollande promised on Sunday to step up

security around synagogues and said the government would soon

present legislation to parliament that would allow police to

arrest people believed to have been involved in

terrorism-related activity outside France.

The Socialist government is taking a hard line on terrorism,

saying no act will be tolerated, as it tries to avoid a repeat

of the bloodshed in Toulouse.

The incident prompted authorities to raise the terrorism

alert in the Toulouse region to "scarlet", the highest level -

the first time this had been done in France.

That was later reduced to "red", where it had been since

coordinated attacks on the London transport system in 2005.

(Reporting by Catherine Bremer and Alexandria Sage; Editing by

Kevin Liffey)

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