Spain's first general strike in eight years has been sparked by government attempts to cut employment benefits.

The centre-right government of Jose Maria Aznar says it is trying to tackle unemployment by increasing incentives for people to find jobs.

But after six years in power, Mr Aznar is now in a head-on confrontation with the unions.

The proposed changes would force the unemployed to take one of the first three "acceptable" job offers put to them, if they were within 30km (20 miles) of their homes.

Aznar has previously had good relations with unions

If they refused, they would lose their benefits.

Other proposed changes would reduce the benefits available to Spain's casual farm labourers.

And anyone sacked from their job but appealing against the decision would lose their salary entitlement during the period of the appeal.

Summit embarrassment

Unions say the reforms undermine workers' rights, and are furious that the government has imposed the changes by decree, in defiance of the strike call.

The strike has been timed to cause maximum embarrassment to Mr Aznar, being staged on the eve of a European Union summit in Seville.

Union members say workers' rights are under threat

Spain will try to minimise disruption to the summit itself, but it may prove difficult to disguise it altogether.

Some of the visiting prime ministers will avoid the disruption by arriving on Friday morning. Other ministers who have to attend pre-summit meetings will be flown into military bases.

General strikes are relatively common features of Spanish political life.

Unlike the UK, which has not seen one since the 1920s, Spain has had four since the restoration of democracy in 1977.

All the others were against socialist administrations.

The last one, in 1994, was in protest against the policies of Prime Minister Felipe Gonzalez.

Under his administration, unemployment had shot up, reaching peaks of 22%.

It looks like the unions will be quite successful in halting the country to a certain degree

Jordi Gual Economics professor

An estimated 50% of union members supported the strike, enough to cause widespread disruption.

The conservatives returned to power in 1996, and Mr Aznar has lowered the unemployment rate to 11.3% - still the highest in the European Union but significantly lower than before.

His government's relations with the labour movement have been generally good, but the benefit reforms have proved too much for the unions to stomach.

More than half a million workers are expected to heed the strike call this time - out of a total membership of 1.8 million in the unions taking part.

Despite the relatively low support rate, the impact of the strike is expected to be significant.

"It looks like they (the unions) will be quite successful in halting the country to a certain degree," said Jordi Gual, a Barcelona economics professor.

Spain is aiming for 2.4% economic growth this year, higher than many of its EU partners.