The Qatari government has pledged to invest 300 million euros (414 million dollars) to recapitalize Spanish savings banks, dpa reported according to Spanish media.
The savings banks known as cajas are seen as the weak link of the country's banking sector. They could play a key role in determining market trust and whether Spain will need an international bailout.
Prime Minister Jose Luis Rodriguez Zapatero obtained the pledge during a visit to Qatar on Monday. He described it as "good news" which signalled Qatari "confidence" in the Spanish economy.
Qatar also promised investments in Spanish telecommunications and energy companies, the daily El Mundo said on its website.
The savings banks hold more than 40 per cent of bank assets in Spain, including billions of euros in bad loans after lending heavily to the housing sector before it collapsed in 2008.
The government has estimated the cajas' liquidity needs at about 20 billion euros, but many analysts believe they could need considerably more.
The government is carrying out a sweeping reform of the sector, including liquidity injections from a bank restructuring fund.