Spain's jobless rate surpassed 20 per cent in the first quarter, its highest level since 1997, a newspaper reported yesterday citing figures accidentally posted by the national statistics institute INE ahead of schedule.

The number of unemployed surged by 286,200 people during the first three months of the year over the final quarter of 2009 to reach 4.612 million people or 20.05 per cent, conservative daily ABC reported.

The figure was posted on INE's website on Monday for several minutes, it said. INE will publish first quarter unemployment figures on Friday.

Spain's unemployment rate stood at 18.83 per cent in the fourth quarter of 2009 with 4.326 million people out of work, according to INE figures published on January 29.

In a statement, INE confirmed that a technological "incident" had made "certain data" from its quarterly unemployment study visible on its web site but it did not confirm the figures published by ABC.

The country is grappling with a collapse of its labour-intensive construction industry at the end of 2008.

It has the highest unemployment rate in the 16-nation eurozone and accounts for half the region's job losses over the last two years, according to the European Union's statistics office.

The continued rise in the unemployment rate could make Spain's socialist government, which is struggling to rein in a ballooning public deficit which has rattled financial markets, spend more on benefits.

Earlier this month Bank of Spain governor Miguel Angel Fernandez Ordonez warned that "mass unemployment" was the greatest risk faced by the country's banks, which will suffer from less business and higher defaults as a result.