An investigator stands beside the wreckage of a car in Palmanova, Mallorca. Photograph: Dani Cardona/Reuters

Spanish authorities have closed ports and airports on Mallorca after two police officers were killed in a bomb attack on the island.

The armed Basque separatist group Eta is suspected to be responsible for the explosion early this afternoon, which reportedly hit a police car on patrol in a street about 400 metres from the town's tourist-packed beaches.

Spanish media reported that an unknown number of people were injured in the blast near the Civil Guard's Palmanova barracks, which is close to several hotels.

It was unclear whether the bomb was attached to the underside of the car or planted in the street.

A regional interior ministry statement said security forces had sealed off the island "to avoid the escape of the terrorists".

Yesterday, a 200kg bomb targeting dozens of Civil Guard members and their families, including children, ripped through their 14-storey barracks building in Burgos, northern Spain.

The attack injured 65 people, including five children, but none of them seriously.

The two attacks coincide with Eta's 50th anniversary and appear to be an attempted show of strength after several months in which it has been hemmed in by police in Spain and France, with several arrests.

Fifty years ago tomorrow, a letter announcing that a group of young radicals had split from the non-violent Basque Nationalist party to form Eta reached the party's leadership.

Source: Guardian.co.uk