MADRID (AFP) -- Spain's interior minister blamed the armed Basque separatist group ETA for an explosion on Monday in the east of Madrid, which police said caused extensive damage but no casualties.

Alfredo Perez Rubalcaba made his comments to journalists while visiting the site of the bombing, in the business district of Campo de las Naciones.
The militant separatist organization was reacting to the Spanish courts' decision late Sunday to ban two separatist parties, ruling they were being used by ETA as an electoral front, Rubalcaba said.
ETA's political wing, Batasuna, has already been banned.
The explosion of the van left a crater one meter (three feet) deep and damaged more than 30 vehicles, a police statement said. It was heard throughout the district.
The blast came just three weeks ahead of regional elections in the northeastern Basque region.
Rubalcaba said the van used in the attack was stolen the day before in the Madrid region, but that ETA did not have an active cell in Madrid.
The last attack claimed by ETA in the capital dates back to the December 2006 airport bombing that killed two people and effectively ended a truce between the militants and the socialist government.
Monday's device exploded on Ribera del Loira street, not far from the offices of a subsidiary of the Spanish construction group Ferrovial, which has been working on a high-speed rail project in the Basque Country.
On December 3, ETA gunmen shot dead businessman Ignacio Uria Mendizabal, 71, whose company was involved in the project. Media reports said the group had warned contractors working on it that they would become targets.
At a press conference Monday in the northeastern Basque city of Bilbao, Juan Jose Ibarretxe, head of the Basque regional government, also blamed ETA for the Madrid bombing.
Both police and Red Cross officials said no one had been hurt in the blast, which went off at around 9:00 am.
Anonymous calls to the emergency services and the Red Cross had warned there was a bomb an hour and a half before it exploded, giving police enough time to locate the vehicle and cordon off the area.
A Red Cross spokesman said Monday that ETA had normally claimed its bombings when it phoned in warnings of previous attacks. On this occasion the caller did not identify ETA as being behind the attack.
But four years ago to the day, ETA carried out a car bomb attack in the same district a few weeks before the 2005 regional elections, loading a car with 30 kilos (66 pounds) of explosives. That blast injured about 40 people.
ETA has been blamed for the deaths of more than 825 people over the last 40 years in its bloody campaign for an independent Basque country in parts of northern Spain and southwestern France.
“When I arrived at the office at 8:25 am, the police were everywhere, there were helicopters overhead,” said a 29-year-old French citizen working in the district.
“Police had set up a security cordon. We were told that there was a bomb alert, that we should stay away from the windows. And all of a sudden, 'boom'.”
The blast was strong enough to rattle the windows and shake the computers on their work stations, he added.