WARSAW (Reuters) - Police have seized more than 1,000 kg of hashish and arrested 23 people in a joint operation in Spain, Poland, Denmark and France targeting a drug smuggling gang, Polish and Spanish police said on Friday.

The gang leaders were arrested in raids co-ordinated by the European Union’s law enforcement agency Europol in the southern Spanish towns of Marbella, Estepona and Lebrija, police said. Among those arrested were 12 Poles, seven Spaniards and two Ukrainians.”At the start we thought the gang operated only in Spain, but later it turned out they were active across Europe with the drugs being delivered to Scandinavia and Britain among others,” Jaroslaw Szymczyk, the head of Polish police, told a news conference.

“This great success would not have been possible without the cooperation between the Europol, Polish and Spanish police forces as well as from other EU countries,” said Michael Rauschenbach, Head of Operations for Serious and Organised Crime at Europol.

The suspected leader of the group - aged 47 and nicknamed “Bandit” - had served a prison sentence in Poland for belonging in the 1990s to a Polish organised crime group called Pruszkow, police said.

Pruszkow was once one of the most notorious gangs in Poland after its 1989 transition from communism. The gang was known for extortion, drug and alcohol smuggling, kidnapping and killing. Many of its high-ranking members were prosecuted in the early 2000s.

(This version of story corrects surname in 4th paragraph to Rauschenbach)