The European Union should be more specific about how it would support Greece in a crisis, to help lower the highly indebted country's borrowing costs now, Greek Finance Minister George Papaconstantinou said on Thursday.

In an interview with Reuters, he also said that while Greece respected the euro zone's principle of dealing with fiscal problems by itself, it did not rule out seeking International Monetary Fund assistance but was not actively pursuing it.

If the EU gave a clearer indication of the mechanism that might be used, in an emergency, to help Greece, bond spreads would fall and a rescue would not be needed, Papaconstantinou said.

The best deterrent is the one that you put on the table for everyone to see and you never have to use it. That's what the markets are looking for, he said.

Bond markets were probing to see whether there was a genuine backstop for Greece because last week's statement of political support by EU leaders was short on specifics, given the reluctance of a number of countries to go further.

Greece needs to borrow or refinance some 53 billion euros this year, more than 20 billion of it in April and May. Investors are charging a risk premium of about 330 basis points to buy Greek 10-year debt rather than benchmark German bonds.

The minister said lowering borrowing costs would help him meet a commitment to the EU to reduce the budget deficit by 4 percentage points of gross domestic product this year.

If you have a clear (EU) statement of intent, then my spreads will collapse with a week, and therefore my assumptions within the (deficit reduction) programme will turn out to be right.

(reporting by Dina Kyriakidou and Paul Taylor)