Although no one claimed responsibility, police were examining recent explosions by anarchists using similar devices for clues, the top representative of the Madrid government in the Catalan region said on Tuesday.

"In Barcelona, there have been some protests from support groups of prisoners of the same ideology in Italy," Joan Rangel told local radio.

But police in the northeastern Spanish port city said they could not confirm anarchists were behind the blast and were keeping an open mind in their investigations.

"The police were warned of a suspicious looking coffee-maker in the doorway of the Italian Institute in Barcelona ... when police were investigating the device, it exploded, injuring the policeman and killing a sniffer dog," a police spokesman in Madrid said.

Spanish national radio said the policeman was hurt in the arm and witnesses said an employee of a medical institute next door had alerted the police after seeing the coffee-maker with wires protruding from it placed in front of the Italian centre.

Anarchists suspected

Italian anarchists claimed responsibility earlier this year for a wave of letter bombs that exploded outside police stations in northern Italy.

Italy has been plagued in recent years by a series of small-scale bomb attacks blamed on shadowy anarchist groups bent on undermining the country's government.

Italian police carried out more than 100 raids in May and said they had uncovered a "vast and dangerous" anarchist network which had orchestrated the bombing campaign.

Interior Minister Giuseppe Pisanu has compared the anarchist movement to Italy's Red Brigades, a 1970s Marxist guerrilla group that orchestrated bombings and kidnappings.