Worried investors forced up Spanish sovereign debt yields on Friday to 6.31 percent, or 494 basis points above the rate on benchmark Germany bonds, the highest gap since the adoption of the euro.
Fears of a possible Greek exit from the euro accelerated a flight to the perceived safety of German bonds, whose yields dipped to a historic low of 1.37 percent.
Pressure on Spanish bonds increased after the head of Spain's largest autonomous region, Catalonia, asked Madrid to help the regions as they encounter increasing difficulty raising funds in financial markets.
The gap between Spanish and German bonds fell to 457 basis points during intraday trading on Friday, but soared to 494 by the close.
Though the yield gap between Spanish and German bonds breached the 500-basis-point level several times last week in intraday trading, the 494 points at the end of trading Friday marked the highest-ever close in the euro era.
A strategist with IG Markets, Daniel Pingarron, said Friday's rise in Spain's country-risk premium was due in part to large purchases of French debt by institutional investors.
He added, however, that the main factor driving markets was Belgian Foreign Minister Didier Reynders' comment that Europe needs to prepare for a possible euro exit by Greece.
Spain has pledged to bring its deficit down to 5.3 percent of its gross domestic product this year, as required by the European Stability Pact, yet it almost must tackle sky-high employment in a contracting economy.
The 2008 global financial meltdown came as Spain was struggling with the bursting of a decade-long real estate bubble. The ensuing slump has led to numerous business failures and pushed the country's jobless rate to above 24 percent, representing more than 5 million people out of work. EFE