The death toll in the bomb attacks on four Madrid commuter trains has reached 200, and more than 260 of the 1400 people injured remain in the hospital, many in critical condition. The government suspects the Basque separatist group, ETA, carried out the attacks, but it is not ruling out a link with al-Qaida.

Interior Minister Angel Acebes said Saturday the ETA Basque terrorist group was still the prime suspect. While he did not rule out a possible al-Qaida collaboration or responsibility, he said two main sources of evidence are being closely examined.

One is a stolen white van abandoned near the train station of Alcala de Henares, where the four commuter trains left for Madrid's Atocha station. The other lead is a sports bag containing an unexploded bomb found aboard one of the trains.

However, a Madrid radio report quoted an unidentified intelligence source as saying evidence collected so far indicates the bombings were probably carried out by Islamic radicals.

Mr. Acebes said a witness saw three men wearing ski masks emerge from the van and move to the train station with bundles. Security cameras in the station are being closely scrutinized to determine their identities. The van contained clothing, detonators like those used in the bombs placed in the trains, and an audio tape in Arabic with verses from the Koran.

The bag found on the train contained explosives with a detonator, shrapnel and a mobile phone timed to set the bomb off.

Mr. Acebes said there was no evidence of a suicide bombing. He also denied allegations from opposition Socialist and United left leaders that the government was withholding information.

Who is responsible for the terrorist attacks is of considerable importance in Sunday's general election. If the public believes ETA carried out the attacks, it would strengthen support for the ruling Popular Party, which has severely curtailed the activities of the terrorist organization. But if al-Qaida is responsible, voters could castigate the Popular Party for supporting U.S. operations in Iraq, which are highly unpopular in Spain.

The last published opinion polls give the governing Popular Party a scant four to six point margin, indicating it could lose its absolute majority in parliament.