One man has been killed and another seriously injured when a man brandishing a baseball bat entered a mosque in the town of Arras in northern France and started beating worshipers, a police source has said.

The assailant identified only as "Seddik" - his first name - carried out the attack in the tiny Ennour mosque in the city of Arras shortly after afternoon prayers, said Abdelkader Aoussedj, of Paris' main mosque.

"The entire Muslim community - and everybody else - is shocked about what happened in Arras," Aoussedj said. "We share in the pain of the victims' families and all the faithful at this mosque."

He was held after the incident on Friday, and was described by police sources as having a history of psychiatric problems.

Denis Robin, the Pas-de-Calais prosecutor, said the attacker was a member of the Muslim community in Arras, and known to the other worshippers in the mosque.

Two other people were slightly injured in the attack, the police source said.

Such attacks are virtually unheard of in France, which is home to Western Europe's largest Muslim community - estimated to be about 5 million people. Many trace their roots in former French colonies in north and west Africa.

Source: Agencies