Spain's risk premium over Germany rose to 436 basis points on Monday after Italian Prime Minister Mario Monti announced he would resign and trigger early elections. The 10-year Spanish-German spread was up 20 basis points from Friday but still well below highs of over 650 bps hit in July.

"Every time there are doubts ... for example today in the case of Italy, when there are uncertainties about the political stability of a neighboring country such as Italy, that immediately affects us," de Guindos said in an interview with the Spanish state radio.

Of a potential request for European Central Bank intervention in the debt markets, de Guindos said: "It is an instrument that the Spanish government is considering and we will take the decision that is best for Spain."

For the ECB to intervene, Madrid would first have to seek help from the euro zone's rescue fund.

The comments by de Guindos came after Spain's biggest selling newspaper El Pais demanded in a front-page editorial that the government urgently request a bailout to help it ride out the economic crisis.

"Postponing a request for an intervention by the European Central Bank in the market is equivalent to condemning the economy to a prolonged recession which will dramatically turn into a major increase in unemployment," the left-leaning El Pais said in the editorial published on Monday.

Hit by an economic slump that has left one in four out of work and saddled with high debts, the center-right government faces a huge battle to rebalance its economy.

But with the country's 2012 funding needs covered, Prime Minister Mariano Rajoy has steered clear of applying for international aid. Such a request would trigger buying of the country's bonds under an ECB program.

The ECB's announcement of its bond-buying the scheme has kept a lid on Spanish borrowing costs since September. But debt yields remain uncomfortably high for a country facing another year without economic growth.

Yields rose on Monday, with benchmark 10-year paper up 14 bps on the day at 5.63 percent as political upheaval in Italy soured investor sentiment towards the euro zone's other lower-rated sovereigns.

El Pais said Madrid should act quickly to reach a decision that Spanish voters, companies and financial markets think will happen sooner or later.

"If the risk premium is not reduced urgently (...) investor mistrust towards Spain will remain and the exit of the recession will be uncertain and late, perhaps after 2014," the paper said.

However, de Guindos said he saw some signs of optimism in the Spanish economy which would contract by between 1.3-1.4 percent in 2012 instead of a previously forecast 1.7 percent slump.

(Reporting by Jesus Aguado, Editing by Fiona Ortiz/Mike Peacock)

• A Permanent Economic Emergency