Italian police have arrested four of six men they suspect are members of an Islamist militant cell which was planning attacks in the United States, Israel and Italy, though no specific targets were named by police.

The men aimed to train militants and send them abroad, para-military police said, and are suspected of conspiracy to commit international terrorism and inciting racial hatred.

They were arrested in Andria in the southern Italian region of Puglia, where police say the group was based, and in Milan, Brussels and Catania, Sicily, and include a Tunisian who was the former imam at a mosque in Andria, police said.

Italian police are still looking for two other Tunisian men who they believe have returned to their home country. No international arrest warrant has been issued for them.

Investigators believe the six men tried to recruit among illegal immigrants in Italy, who then went on to training camps in Afghanistan, Chechnya, Iraq and Yemen.

In some cases the new recruits carried out attacks in Iraq.

The cell was characterised by "fierce anti-Semitism and anti-Western sentiment" and aversion to states viewed as enemies in the context of religious war, a police statement said.