Tens of thousands of demonstrators have marched in dozens of Spanish cities to protest against sky-high unemployment, corruption scandals and what they say is the government's inefficient handling of the economy, Belfast Telegraph reported.

Many protesters carried placards critical of Prime Minister Mariano Rajoy's ruling Popular Party, which is immersed in a corruption investigation centred on former treasurer Luis Barcenas and alleged under-the-table payments to party officials while in opposition.

King Juan Carlos' son-in-law, Inaki Urdangarin, is also under investigation on suspicion of having embezzled several million dollars.

Rallies were organised in Madrid and 60 other cities by 150 organisations including trade unions representing the construction, car and television industries as well as police and health services. Police estimated some 20,000 people marched in the north-eastern port city of Barcelona, but authorities did not have figures for a large rally held in Madrid.

Spain's unemployment rate is at 26% and the economy is immersed in its second recession in three years, with many young graduates and qualified professionals emigrating to find jobs elsewhere.