Our weapons are words, we have moral superiority, the courage of our convictions and the certainty we will win with peace

Luis Partida, local government official

The protesters - including senior Spanish politicians - gathered near where an ETA bomb injured 10 people last week, and held a five-minute silence in solidarity with the victims of ETA.

This was the second demonstration to be held in Madrid in a week which has seen a marked escalation in violence blamed on the Basque separatists.

Police investigate the site of Tuesday's bomb

On a platform outside the municipal offices, the representatives of the local government and mainstream political parties spoke to the crowd under a banner which read "Madrid for peace and liberty."

Other demonstrators held placards saying "That's enough" and "ETA assassins".

"Without guns you're nobody", chanted the crowd, and "Basques yes, ETA no."

Luis Partida, a senior official with the Spanish federation of local governments, called for Spaniards to remain strong in the face of the attacks.

Officials have called on Spaniards to remain strong

"Our weapons are words, we have moral superiority, the courage of our convictions and the certainty we will win with peace," Mr Partida said.

His words echoed comments by Prime Minister Jose Maria Aznar on Tuesday in which he rejected ETA's demands for a Basque state as non-negotiable.

"They are not going to force us to our knees, and we are not going to change a policy of which we are fully convinced," Mr Aznar said.

Latest attacks

Tuesday's bomb exploded early in the morning in a shopping centre in Vitoria, causing severe damage but no injuries.

The early morning attack was the fourth in the past week blamed on ETA.

Several hours later, a bomb was found attached to a car belonging to socialist politician Jose Asenjo in the southern port city of Malaga. The device was exploded by police and no one was injured.

ETA has been blamed for about 800 killings in its 32-year-long campaign for independence for the Basque region.