Spain's finance minister warned on Monday that the public deficit for 2011 could surpass eight percent of gross domestic product, a figure announced last week and already beyond the six percent originally forecast.
"It is possible that it exceeds 8.0%, but I hope it won't be much higher," Luis de Guindos told private radio Cadena Ser.
Spain's new right-leaning government announced on Friday that the 2011 deficit would top previous forecasts as it unveiled spending cuts and tax increases to claw back 15.1 billion euros ($19.6 billion) in 2012.
"A big part of this difference (in deficit forecasts) comes from the regions," de Guindos said, adding that he expected them to "make an effort".
Spain's 17 autonomous regions, which are responsible for health and education services, were particularly hit by a 2008 crash in the housing market and are an increasing source of concern for economists and policy-makers.
"Everyone must participate in this effort," the minister said.
"We are in a very difficult situation, very complex, and without a doubt the hardest in the past decades in Spain," he said.
Prime Minister Mariano Rajoy, freshly installed after beating the Socialists in November elections, has vowed to meet Spain's target of reducing the public deficit to 4.4 percent of GDP in 2012.
Madrid aims to narrow the deficit to 3.0 percent of GDP -- the limit agreed by European Union members -- by 2013.
The public budget in European Union terms comprises the budgets of central government, welfare systems and local authorities.
De Guindos said measures to rein in the public deficit would be accompanied by structural reforms in the labour market and financial system aimed at reviving Spain's economy.
"The government has a very aggressive reformist agenda for the next few weeks and months," he said.
"We all must reduce the public deficit but I also believe that we must put in place economic reforms because Europe can't limit itself to a simple economic policy of budget adjustments. It is economic reforms that will allow us to emerge from the crisis."