By James Coomarasamy BBC Paris correspondent

There has been a second petrol bomb attack on a synagogue in the Paris suburb of Garges-les-Gonesse.

The building suffered only minor damage in the attack, which is the latest in series of incidents against Jewish targets across the country. Two petrol bombs were also thrown at the same synagogue at the weekend.

French authorities have stepped up security outside Jewish institutions and arrested over 30 people after an upsurge in anti-Semitic violence.

Police are not revealing the identities of the people who have been arrested.

Increasing concern

The continuing series of attacks on Jewish targets is causing the Jewish community and the authorities in France great concern.

Many of the synagogue attacks, such as the ones in Garges-les-Gonesse, have taken place in poor suburbs where large numbers of disaffected youths from North African backgrounds live.