A car bomb exploded near a Madrid soccer stadium yesterday hours before a European Champions League semi-final match in an attack claimed by the Basque separatist group ETA. A Madrid police spokesman said nine people were slightly injured in the blast, which destroyed several cars. The Basque newspaper Gara said ETA had telephoned it just minutes before the blast to warn of the attack. Shortly after the bombing, a second, smaller explosion was heard on the other side of the city in what authorities said was likely to have been the attackers blowing up a getaway car. The first blast rocked northern Madrid at around 1455 GMT hours before the area was due to be swamped with fans for the soccer match between Real Madrid and Barcelona at the Santiago Bernabeu stadium. The Madrid police spokesman said federal police had received a warning and had alerted the city's police. We surrounded the place and we avoided something worse. We were there...when the car exploded and we are trying now to keep people out of the place, the spokesman told BBC television. ETA has carried out numerous bombings and other attacks in its campaign for independence. A crowd of 75'000 was expected at the stadium for the second leg match which was due to start at 1845 GMT. European soccer's governing body UEFA held a security meeting to decide if the match could go ahead and later announced that it would be staged as normal. The two teams, staunch rivals in the Spanish league, feature some of the world's best and most expensive players. Both clubs, who trained at the Bernabeu on Tuesday night, were staying at hotels in the city centre before the game. Ten days ago a car bomb blamed on ETA damaged buildings and cars in the same area but caused no serious injuries.