MADRID (AFP) -- Standard and Poor's on Wednesday affirmed Spain's credit rating at BBB+ with the outlook still negative on fears that measures to help the eurozone struggler will fall short.

"In our view, Spain's commitment to the ongoing implementation of a comprehensive fiscal and structural reform agenda remains strong," S&P said, referring to a raft of new austerity measures passed by the conservative Spanish government.

But the agency kept the outlook on 'negative,' "reflecting our view of the multiple risks to Spain's economic rebalancing (including) ... the effectiveness of the eurozone policies in stabilising funding markets."

S&P warned that the deep recession which has pushed Spanish unemployment up to a near 25 percent rate puts "an ambitious 6.3 percent of GDP 2012 fiscal target (versus 8.9 percent of GDP in 2011)" at risk.

The debt burden of Spain's 17 regional governments is also a concern as markets fear that strains on the national finances could drive the country to seek a full bailout.

S&P said the national rating would "be influenced by any large and persistent budgetary deviations by the regions relative to their consolidation targets, as these deviations would increase net general government debt."

Last month, Spain turned to eurozone partners to help rescue its banks, which are weighed down by a mountain of bad real estate loans after a property bubble burst in 2008.

Eurozone countries agreed to extend a credit line of up to 100 billion euros ($123 billion) to Spain to shore up its banks if needed.