As the demonstration, called in support of Basque prisoners, set off behind a banner declaring, "The Basque Country Needs Freedom," the police moved to block the street.
It is the largest transfer ever of Basque prisoners, affecting a quarter of the 405 Basque militants, convicted or awaiting trial, in Spanish jails.
Demanding the release of a number of Basque prisoners (a condition largely met by the Spanish government), his captors later demanded a ransom of one billion pesetas and further prisoner releases.
Cenarrusa has also appealed for clemency for Basque political prisoners in Spain.
And good-will gestures the group had asked for such as moving Basque political prisoners to jails near the Basque region were slow in coming.
He moved 135 Basque prisoners to prisons in the Basque Country, one of the main claims ETA has made since the beginning of the dispersion prison policy.
Suárez granted a multi-stage amnesty for numerous Basque political prisoners, but the confrontations continued between local police and protesters.
They want a half-dozen Basque political prisoners in Madrid released from jail.
But the government said it was willing only to discuss possible leniency for hundreds of Basque prisoners and exiles.
In various Spanish and French prisons 18 Basque political prisoners have been undergoing hunger strikes since 1 November.