Armed Basque separatist group Eta has denied responsibility for train bombings that killed at least 199 people, Basque media reported on this evening, citing phone calls from the armed group.
"An ETA message has arrived saying that it bore no responsibility for the attack," a presenter for ETB Basque public television said.
The Basque newspaper Gara also said on its Web site that it had received a phone call from a person claiming to represent ETA saying it "had no responsibility whatsoever" for the attacks which involved 10 bombs set off simultaneously on four trains on Thursday morning.
There was no way to independently confirm the authenticity of the call, but Eta has claimed responsibility for past attacks through ETB and Gara.
ETB said the caller identified himself as one of two masked ETA leaders who last month delivered a videotaped message declaring a partial truce limited to Catalonia region in northwest Spain.
There has been speculation that the manner of the bombings and the scale of the attack indicated possible involvement by Islamist militants, though Madrid insists ETA is the most likely suspect.
Some security analysts have also suggested a militant splinter group of ETA was behind the attacks.
Interior ministry officials were unavailable to comment.
Political leaders in the Basque region were cautious about reading too much into the purported Eta messages.
"This is a day of demonstration, of repulsion and condemnation .... over the massacre of yesterday," Patxi Lopez, leader of the Socialist party in the Basque Country, told reporters at the march in the largest Basque city of Bilbao.
"But it is no less true that we need to know the truth (about what happened)," Lopez said. "I always believe the Interior Ministry more than ETA."