The Spanish Interior Ministry said in a release Friday that three former members of a notorious Serbian crime ring had been arrested in a restaurant in the center of Valencia following a period of Spain's police tracking their activities.

The persons arrested in the Spanish police operation were Luka Bojovic, Vladimir Milisavljevic, and Sinisa Petric, all three being former members of the notorious 'Zemun Clan'.

Bojovic was the 'Zemun Clan' leader, Milisavljevic acted as his deputy, while Petric worked for the clan as a paid assassin and also manage to escape from a Serbian prison, the release said.

Spanish police have been conducting an investigation against several criminals from the Balkans involved in murder, robbery, jewelry, drug trafficking and money laundering for over 20 months, according to the Spanish Interior Ministry's release.

The arrest was preceded by a monitoring operation that lasted for more than 20 months and was run in cooperation with the Serbian and Dutch authorities.

On the day of the operation, police tracked Milisavljevic, who arrived from Las Palmas to meet with the other two criminals at the Valencia restaurant on Thursday, and when the three were all finally there, the police decided to make the arrest, said the Spanish ministry.

The three arrested men were initially members of a paramilitary group 'Arkanovi Tigrovi' (Arkan's Tigers), known for their brutality during the Balkan wars, which later grew into a mafia organization called the 'Zemun Clan', according to the Spanish Ministry.

Bojovic (39) is charged in Serbia with several criminal offenses including involvement in murder, trafficking in drugs, weapons and human beings and offenses related to prostitution.

Investigations against Bojovic, on charges of armed robbery and drug trafficking, are being conducted in Switzerland, Romania, the Netherlands, the United States and Spain.

An international warrant for Bojovic's arrest was issued in September 2010.

Serbian Interior Minister Ivica Dacic said today that the Spanish police had confirmed the identity of people who were arrested in that country last night.

Dacic pointed out that the persons arrested in Spain were Bojovic, Milisavljevic, Petric, adding Vladimir Mijanovic to the list.