PARIS, (AFP) - Terror suspects detained in France had been eyeing up the Parisian metro network, an airport and the headquarters of the domestic intelligence service as possible targets, sources close to the investigation said.

The suspicions were based on an intelligence tip-off from Algeria and from telephone surveillance, although there is no hard evidence they had settled on a particular target, they said.

Nine people were detained by police early Monday in a series of raids west of Paris in what officials said was a crackdown on suspected Islamic terrorist activities.

Among those being held is Safe Bourada, 35, who was released from prison in 2003 after five years for helping organise a series of bomb attacks in France in 1995 for the Algerian Armed Islamic Group (GIA).

Seven of those held were described as targets of the police operation, and the two others happened to be with them when the round-up took place.

Officials said the men were members of the Salafist Group for Preaching and Combat (GSPC), an armed Algerian group that grew out of the GIA and has links to the Al-Qaeda network. Bourada was described as their ringleader.

The GSPC has threatened to carry out attacks in France and it is seen as a credible danger by intelligence officials.

The interior ministry announced later Monday the government has prepared a series of new anti-terrorism measures including increased use of video-surveillance and improved police access to Internet and mobile telephone records amid the heightened threat of terrorism.