Spain's wealthiest autonomous region, Catalonia, needs financing help from the central government because it is running out of options for refinancing debt this year, Catalan President Artur Mas has said.
His region faces debt payments, including refinancing costs, of €13 billion this year, according to Spanish media.
"We are calling for the use of hispanobonos," regional Spanish bonds, Mas told a group of foreign journalists in Madrid.
"The mechanism does not matter to us so long as it assures us of two things; one that we have treasury at the end of each month to make payments because that has an economic impact," he said.
"And second, that it be at an average cost. We would like it to be at an average European cost, but if at the moment it can't be at a European average, at least it should be at a Spanish average."
Madrid blames overspending by the regions for overshooting its public deficit target last year, and it demands they cut their deficits to 1.5% of economic output this year from 2.94% last year.
Last week, the central government approved plans for €18.349 worth of spending cuts this year for all but one of the country's 17 semi-autonomous regions.
The regional governments are considered crucial for Spain to fulfil its promise to cut its overall deficit from 8.9% of output in 2011 to an EU limit of 3% next year.
The collapse of a decade-long property boom in 2008 has caused Spanish regions' tax revenues to drop and their debt levels to soar, and they are struggling to pay suppliers.
Moody's Investors Service last week warned of the deficit challenges ahead as it downgraded its credit rating for Catalonia and three other regions, Murcia, Andalucia and Extremadura.
The New York-based agency cited a "poor fiscal performance in 2011 and the low probability that the regional governments will be able to meet the 2012 deficit target."
Catalonia had its credit rating cut by one notch to Ba1, Murcia by two notches to Ba1, Andalucia by two notches to Baa2, and Extremadura by one notch to Baa1.
The regions remain under surveillance for a possible further downgrade, as does Spain's sovereign A3 rating, said Moody's.