MADRID (AFP) - Spanish police arrested 17 people including six Chinese suspects for a ram-raid on a jeweller's in Madrid that looted luxury watches worth 23 million euros (S$38 million), officials said on Thursday.

The robbery last December was one of Spain's biggest jewel thefts ever, police said in a statement.

The robbers disarmed the jewellery store's alarms and broke into its secure chamber, stealing more than 1,700 luxury wristwatches.

Officers arrested the leader of the gang responsible for the heist along with "a well-known ram-raider" notorious for crashing vehicles through shop windows for robbery.

The six Chinese nationals detained were suspected of receiving the stolen watches and selling them on in China, the statement added.

Police caught those suspects trying to smuggle some of the watches out of Spain in suitcases. The cross-border agency Interpol also helped track down some of the watches in Shanghai.