French banks have reached an outline agreement to roll over holdings of maturing Greek bonds as part of a wider European plan to avoid sovereign default.

Nicolas Sarkozy, the French president, said in Paris on Monday that the banks would be offered 30-year Greek bonds with a coupon equivalent to the euro zone's lending rate to Greece, plus a premium based on the financially troubled nation's future economic growth rate.

"We concluded that by stretching out the loans over 30 years, putting [interest rates] at the level of European loans, plus a premium indexed to future Greek growth, that would be a system that each country could find attractive," Sarkozy said.