Spain has paid the highest rate since 1997 to sell its ten-year debt in a bond auction this morning.
It paid 6.975% - a 7% level is seen as unsustainable.
Investor fear has spread rapidly through the single currency area, from Greece and Italy to Spain, which faces general elections on Sunday, and even AAA-rated France.
Countries at the fringes of the eurozone have seen their financing costs leap this week over fears that Italy could eventually default.
Spain's government was forced to pay an average yield of 6.975% for today's bond, the highest since 1997 when the average yield was 7.26%.
The highest paid this year on a separate 5.5% coupon ten-year bond was 5.986% on 21 July.
The bid-to-cover ratio in the Spanish auction, an indicator of investor demand, was 1.5, down from 1.8 in October for a similar bond.
In a separate auction, France's cost of borrowing over two and four years jumped by around half a percentage point, reflecting growing concerns it may be dragged into the eurozone's sovereign debt crisis.
Martin wants Taoiseach outline euro stance
Fianna Fáil leader Micheál Martin said today that Taoiseach Enda Kenny needs to explain Ireland's negotiating position on the eurozone crisis to the Irish people.
Yesterday, Mr Kenny held talks in Berlin with German Chancellor Angela Merkel at which differences emerged between the two leaders on how to deal with the crisis.
Speaking on RTÉ’s Morning Ireland, Mr Martin said there was a need to have a genuine debate in the Dáil on the issue.
He said he believes there are only weeks left to save the euro.
Mr Martin said France and Germany have been allowed take centre stage of a crisis that is ''euro-wide'' and for which a ''euro-wide'' solution is needed.
He said some of the pronouncements made by France and Germany in recent months have made the crisis worse.
Mr Martin also said that while his party was in favour of limited treaty change, particularly in relation to the European Central Bank mandate, immediate measures were needed to resolve the crisis.
The gap in borrowing rates between French and German government debt also widened to more than 2% this morning, the widest spread since the creation of the euro.