MADRID - Spanish police said Monday they had smashed a criminal gang who preyed on tourists in Madrid by posing as police officers.

Eight suspected members of the gang, all of them Iranian and Pakistani nationals, were arrested on November 22, police said, describing a grab-and-game game to take cash, jewellery and smartphones.

The gang would approach tourists and ask to see their documents and wallets "with the pretext of checking to see it they had drugs or counterfeit money," police said in a statement.

"Once they had the wallet in their possession, they would remove the cash or would yank any object of value and flee at great speed."

Police suspect the ring is behind at least 21 robberies carried out in the Madrid region in recent months but say the number is likely higher many victims, visiting Spain briefly, did not file complaints.

Among the loot recovered during the arrests in three suburban Madrid homes, included 10 high-end watches, 15 smartphones, jewellery as well as 1,000 euros ($1,070) in cash. They also seized six vehicles which the gang is believed to have used in their robberies.