Spanish judges staged an unprecedented strike today, to call for more resources for courts they say struggle under an intolerable workload using outdated technology.

At least 63 percent of Spain's roughly 3,500 serving judges joined the one-day protest, which will be followed by another stoppage in June unless their demands are met, according to the Francisco de Vitoria Legal Association, one of the groups organising the strike.

Judges and state prosecutors demonstrated outside courtrooms in several Spanish cities to demand the government hires more judges and limits their workload.

They also want the legal system, which still largely works on paper, to be fully computerised.

Grumbling within the justice system rose last year when a judge was fined for failing to ensure a convicted child molester was put in jail, an oversight which led to the murder of a five-year-old girl in Huelva.

Legal officials say they are unable to cope with the volume of work and should not be blamed for failing to complete all their tasks.

The government says it is doing what it can to modernise the courts and that judges do not have the right to strike.

Despite the strike, judges have guaranteed minimum service for essential matters, such as arrests and marriages.