Italian police carried out a series of arrests Thursday as part of an investigation into an outlawed Turkish Marxist group responsible for a series of attacks in Turkey, news reports said.

Police in Perugia (search), who are coordinating the raids, confirmed arrests were taking place but refused to provide any details, saying the operation was still in progress. An official described the operation as aimed at "international terrorism" but declined to be more specific.

About 100 police and Carabinieri paramilitary forces took part in the raids in Perugia, a city about 80 miles north of Rome (search) with a high percentage of foreigners mainly due to a university that attracts students from abroad.

Italian news agencies ANSA and AGI and state-run RAI TV said some suspects were picked up in Turkey as part of the same probe, as well as in Germany, the Netherlands and Belgium.

Turkish police said they had no immediate information on the arrests.

The Italian reports said the arrests broke up a cell of the far-left DHKP-C, or Revolutionary People's Liberation Army/Front (search) — a group that is branded as a terrorist organization by the U.S. State Department and by the European Union.

DHKP-C has claimed responsibility for a number of bombings in Turkey, including two suicide attacks in 2001 that killed three Istanbul policemen and an Australian woman. It has also carried out attacks in Germany.

The banned group aims at toppling the government and replacing it with a Marxist one. Over the years, the DHKP-C and its forerunner, Dev Sol (search), have claimed the killings of generals, police officers, government officials and foreigners. It has also targeted U.S. military personnel and diplomatic missions.

The group is reported to have some 1,000 followers.

In September, Istanbul police announced they had captured two DHKP-C militants suspected of plotting suicide bombings. A woman believed to be part of the group died in May after her bomb apparently exploded prematurely in the restroom of an Ankara cafe.

Italy has been on high alert against terrorism since the Sept. 11 attacks. After the bombings in Madrid earlier this month, Interior Minister Giuseppe Pisanu told law enforcement agencies across the country to be extra vigilant.

Pisanu cited Perugia as one of the Italian cities at greater risk of terror attack, along with Rome, Milan, Naples and Bologna.