Turkish police say another 10 suspected militants have been arrested in sweeps against a militant Turkish group in Turkey and four Western European countries, raising the number of detainees to 63.

Raids in Turkey, Italy, Belgium, Germany and the Netherlands began early Thursday, targeting the Revolutionary People's Liberation Party Front, which has called for the overthrow of the Turkish government.

Earlier, police said 53 suspected members of the Turkish group had been taken into custody in coordinated raids in the five countries. The crackdown comes ahead of a planned NATO summit in Istanbul in June.

Authorities say Turkish police and intelligence officials and their Western European counterparts had been planning for the operation for more than a year.

The United States and European Union have classified the Turkish Marxist group as a terrorist organization.

The Revolutionary People's group is responsible for a series of attacks in Turkey, including suicide bombing in Istanbul that killed two police officers and an Australian woman in 2001. It is also believed to be behind the murders of more than 100 policemen, generals and government officials, including a former Turkish justice minister. The militants also have targeted U-S military personnel and diplomatic missions.

In a separate arrest Thursday, authorities in northern Greece arrested a German man accused of links to the same group. He had been stopped for an identity check. His arrest was not part of the wider operation.