Greece on Thursday said it was looking for alternative options to counterbalance the effects of a planned European Union embargo on Iranian oil imports on its struggling economy.

"Greece has expressed certain concerns regarding the effects of taking such measures on European economies," foreign ministry spokesman Grigoris Delavekouras told a news briefing.

"The competent authorities in Greece have examined, and continue to examine, possible supply from other sources," he said, without elaborating.

After weeks of fraught talks on an embargo which could hurt debt-straddled European Union nations, EU ministers last month agreed on an immediate ban on oil imports and a gradual phase-out of existing contracts between now and July 1.

Crisis-hit Greece imports around a third of its oil from Iran at advantageous credit terms. Italy and Spain are also major Iranian oil importers.

In the toughest action yet against Iran's ability to fund its nuclear programme, the EU outlawed petrochemical imports and investments and banned the sale of gold, diamonds and other precious metals.

The EU and the United States seek to force Tehran to return to negotiations amid concerns it is inching ever closer to building a nuclear bomb.

The EU imported some 600,000 barrels of Iranian oil per day in the first 10 months of last year, making it a key market alongside India and China, which has refused to bow to pressure from Washington to dry up Iran's oil revenues.

"We want a solution and we want cooperation," Delavekouras said. "We believe in diplomacy," he said.