ETA is suspected for an explosion that hurt the bodyguard of a local politician in Bilbao, the police in northern Spain informed. The armed Basque separatist group was expected to act in response to the detaining of the leaders of their political wing last week.

The bomb was detonated when the bodyguard opened the door of the car in the central Bilbao. His injuries were labeled as moderately serious by the medical crew which took him to the city hospital. The guard was alone in the car which normally carries the Socialist councilor.

"I saw a man rolling across the ground to escape from the blast,'' Antonio Rodriguez, who witnessed the scene, told CNN+ Television channel.

The reaction followed the imprisonment of the entire leadership of Batasuna, the illegal party regarded as ETA's political wing. On Sunday, seventeen of the 23 detainees were jailed.

The government announced on Tuesday that security in the Spain will increase as the authorities were expecting ETA to fight back. In Madrid the were extra police forces deployed to make sure that there will be no disturbances on Friday, the day when King Juan Carlos is to watch a military parade to mark National Day.

The terrorist group ended the one year-old cease-fire in June as peace talks with the government of Prime Minister Jose Luis Rodriguez Zapatero failed. Since then the separatist faction set numerous bombings. The worst of them injured two police officers.

ETA - Euskadi Ta Askatasuna (Basque for Basque Homeland and Freedom) – is held responsible for more than 800 deaths over the last four decades. As their group name suggests, they fight for an independent Basque country covering parts of what is now northern Spain and southern France.

ETA is part of a faction informally known as the Basque National Liberation Movement. This movement contains several distinct organizations that promote a type of leftist Basque nationalism. Other groups considered to belong to this movement are: the political party Batasuna, the nationalist youth organization Segi, the labor union Langile Abertzaleen Batzordeak (LAB), and Askatasuna among others. There are strong interconnections between these groups as double or even triple membership is common according to the Spanish Authorities.