Ankara, Turkey ? Turkey, Italy, and Belgium arrested 53 militants in a coordinated crackdown Thursday on a Turkish Marxist group considered a terrorist organization by Washington, Turkey’s Interior Ministry said.

Police in Istanbul arrested 37 suspects of the Marxist Revolutionary People’s Liberation Army-Front, or DHKP-C, while security forces Italy and Belgium detained 16, an Interior Ministry official said, speaking on condition of anonymity.

Turkish and German police have been preparing for the crackdown for the past year, while the Italian police became involved more recently, the official said.

German and Italian police discovered during their investigations that the group also was active in the Netherlands and Belgium and coordinated the European crackdown outside of Turkey, the official said.

The DHKP-C seeks to topple the Turkish government and replace it with a Marxist one. The group and its forerunner, Dev Sol, have 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 and has targeted U.S. military personnel and diplomatic missions.

The group, which is branded as a terrorist organization by the State Department and by the European Union, was active before the 1980 coup in Turkey but has become increasingly marginalized due to a harsh police crackdown.

Several leading members of the group fled to Europe, where it is believed the group has hundreds of sympathizers.

Police earlier said that a suspected DHKP-C militant was injured in Istanbul Thursday, reportedly when a bomb he was making exploded. But police later said the blast was a gas explosion in a home and that the injured man, Hasan Midilli, was not part of any militant organization, the Anatolia news agency reported.

In Italy, police arrested five people Thursday in the central town of Perugia, Italian Prosecutor Nicola Miriano said. About 100 police and Carabinieri paramilitary forces took part in those raids.