Estimates varied widely with police saying 2,000 people turned out in Madrid while organizers put the number at 30,000.

A two-hour, rotating general strike for next Thursday was called by one of Spain's main unions, the UGT.

It will be one of a string of anti-war efforts -- including legal action against the government -- organized in Spain where public opinion is overwhelmingly against their government's staunch support for the US-led military strikes on Baghdad.

A group called "No to War", made up largely of opposition paraties, union members, non-governmental organizations and cultural associations, also called for new, mass anti-war marches across the country at 6:00 pm on April 10.

Another group, "Culture Against the War", will hold an open-air concert in the capital on Sunday where various personalities have said they will voice opposition to Prime Minister Jose Maria Aznar's support for the US-led war on Iraq.

Organizers said a message would be read out by Spain's top anti-terrorist judge Baltasar Garzon, who cannot attend due to court duties, by his daughter.

Another group, the NGO Center for the Study and Defense of Human Rights, meanwhile said it planned take legal action against Aznar, charging that his support for the US-led war on Iraq is illegal.

A broad coalition of anti-war activists, militant lawyers and judges have filed a similar action, although Justice Minister Jose Maria Michavila Wednesday dismissed the lawsuits as "unfounded".

The legal complaints accuse Aznar of breaking Spanish law by involving Spain in a military conflict without authorization from both houses of parliament and the King, who is head of state.

SPACE.WIRE