Thousands of people filled the streets of Bilbao, in Spain’s Basque country, just hours after a judge rejected efforts to ban the rally.
Marchers are demanding more rights for jailed members of Basque separatist militants, ETA. In particular they want an end to the policy of sending detainees to prisons hundreds of kilometres away from home.
Cries included “Basque prisoners to the Basque country” and “No peace without amnesty”.
A Madrid judge allowed the demonstration providing those taking part did not express support for ETA.
The European Union and the United States consider ETA a terrorist organisation and it is held responsible for more than 800 deaths in its 41-year struggle for independence for the Basque country.
Spain has just raised its terror alert level after warnings ETA may be planning attacks during Madrid’s six-month EU presidency which began on New Year’s Day.
Thousands march for ETA prisoner rights