Uncertainty over whether Spain intends to seek a full bailout is "highly risky", Joaquin Almunia, the EU's competition commissioner, warned Madrid during an interview with AFP.
Almunia, who represents Spain in the 27-member EU executive, recognised that Prime Minister Mariano Rajoy faced "a difficult decision" in having to choose whether to ask for a sovereign rescue rather than financial aid merely for its troubled banks.
"It's not a black or white decision," Almunia said.
"But what's highly risky is to maintain the uncertainty, because you can come to a time when the cost of that uncertainty is bigger than any decision."
Recession-hit Spain is under pressure to request a bailout as its financial system grinds to a standstill and with one in four adults listed as unemployed.
But Rajoy has been holding off making a decision on whether to request a bailout from Spain's eurozone neighbours because it is not clear what conditions they would attach to the aid -- such as demands for more specific budget cuts.
Almunia stressed that should Madrid go for the full bailout option, there would be no new conditions bar "a precise calendar" for implementing reforms.
"The type of conditionality the Commission has in mind for situations of this kind would be to set out a precise calendar of decisions stemming from recommendations made by the Commission," he said.