The IMF's role is politically sensitive, as the Fund has been blamed for tough austerity measures elsewhere
Spanish borrowing costs roared to a euro-era record high Tuesday on a market beset by doubts over a vast rescue loan for the country's banks and by fears of a Greek exit from the eurozone.
Markets appeared to be in alarm despite eurozone powers striking a deal on Saturday to extend Spain a banking sector rescue loan of up 100 billion euros ($125 billion).
Two major concerns stood out: doubts over Spain's outlook even with the eurozone rescue, and Greek elections on Sunday, which in a worst-case scenario could send Athens back to using the drachma.
Adding to the Spanish agony, Fitch Ratings downgraded 18 more Spanish banks a day after cutting its ratings on the two biggest banks, Santander and BBVA, despite the massive sector bailout.
Fitch warned that some Spanish banks' loan portfolios could deteriorate further, especially those exposed to the collapsed real estate sector, and said the weak markets made it tougher for them to find financing.
It was impossible to say how things may turn out, warned Edward Hugh, an independent economist based in Barcelona.
"This thing is like an express train accelerating towards the buffers in the station," he said.
"You have got this cocktail now with the Greek elections coming this weekend and talk of capital controls over Greece, you have got Italy coming back into the line of fire and then you have got this uncertainty about Spain."
Spain's benchmark 10-year government bond yield spiked to 6.834 percent, the highest since the creation of the euro, and by late afternoon was at 6.716 percent -- a cost regarded as unsustainable over the longer term.
The nation's risk premium -- - the extra rate investors demand to hold its 10-year bonds over their safer German counterparts -- hit 5.43 percentage points, not far from the euro-era record of 5.48 percentage points struck shortly before the banking rescue.
Markets also punished Italy, at risk of being the next domino to fall in the eurozone crisis as it struggles to boost growth and confronts a public debt mountain of 1.9 trillion euros.
Italy's 10-year government bond yield leapt to a high of 6.301 percent from the previous day's closing level of 6.032 percent.
Far from calming the markets, the rescue for Spain exposed a string of new doubts over the impact on the debt; how it will be implemented; and whether it will be just the first rescue for a nation struggling to cut deficits in a period of recession and sky-high unemployment.
Spain was expected formally to seek the loan at a eurozone finance ministers' meeting June 21, and a final figure would come after a review by the European Union, European Central Bank and IMF, officials said.
A report by Barclays Capital analysts said that a loan of 70-80 billion euros would push up Spain's public debt by 7.0-7.5 percentage points from the end-2011 level of 68.5 percent of economic output.
Under this scenario, Spanish public debt would likely peak at 95 percent of economic output by 2015, they predicted.
One key concern for bond buyers is whether the eurozone bailout for Spain would tap the incoming bailout fund, the European Stability Mechanism (ESM), whose debt takes priority for repayment over ordinary investors in a time of crisis.
Several analysts warned that a Spanish banking rescue using the ESM, which comes into force next month, could have the unintended effect of scaring ordinary investors away from Spanish government bonds.
"If the amount borrowed from the ESM were to materially exceed the currently expected 100 million euros, the ESM's self-declared preferred creditor status could, in our view, constrain Spain's access to the capital markets and therefore reduce the likelihood of bond holders being paid in full," said Standard & Poor's rating agency.
Investors also worried about the prospect of Spanish banks using the new cash to load up on Spain's sovereign bonds, analysts said.
Tiny Cyprus added to the gloom.
Cyprus Finance Minister Vassos Shiarly told journalists on Monday that his country had an "exceptionally urgent" need for a bailout to recapitalise its banks by June 30, according to the Wall Street Journal.
The island's economy is only a 60th of the size of Spain's, it said.
The big spectre, however, remains Greece, and the prospect that the anti-austerity party Syriza will win elections on Sunday, rejecting the terms of Athens' international bailout and leading possibly to its departure from the 17-nation single currency bloc.