All four men are known to police and are suspected of having close links to radical Islam, a judicial source told the AFP news agency on Wednesday.

Three of the men, who are aged between 20 and 42 and whose identities have not yet been revealed, were arrested at their Paris home in the early hours of Tuesday morning and immediately taken into police custody.

The fourth suspect, who is currently in jail on terrorism charges, has been removed from his cell for questioning.