The explosion occurred on Tuesday morning outside the Italian Culture Institute in the center of the Catalan capital. Police say the device, which was contained in a metal coffee pot, left one policeman injured and a bomb-sniffing dog dead.

Although the authorities have received no official statement linking a name to the attack, initial speculations suggests it could be the work of an Italian anarchist group.

Joan Rangel of the Catalan government, who visited the site of the blast, said that authorities were examining recent explosions by anarchists using similar kinds of explosive devices.

He said the Catalan authorities had contacted the Italian consulate in Barcelona a few days ago after having detected "greater activity of anarchist groups" in the city.

Protest bombing

Rangel said there had been a number of demonstrations in Barcelona over the past days calling for the liberation of some prisoners in Italy belonging to the same group as the protesters.

Rangel said the device had been hidden in the doorway of the Italian Cultural Institute. "Police were warned of a suspicious looking coffeemaker in the doorway of the Italian Institute in Barcelona…when police were investigating the device, it exploded," a police spokesman said.

The injured policeman was taken to hospital but is not in critical condition.

Wave of bombings

Earlier this year Italian anarchists claimed responsibility for a spate of letter bombs which exploded outside police stations in northern Italy. The country has been the target of a number small bombs over the past years, thought to be the work of anarchist groups trying to undermine Italy's democracy.

In May, Italian police launched a wave of raids in which they claimed to have revealed a "vast and dangerous" network of anarchists responsible for the bombing campaign.