The European Union on Monday said an Iranian probe into alleged election fraud must answer all complaints made by opposition protesters who say the re-election of President Mahmoud Ahmadinejad was rigged.

"This is a matter that the Iranian authorities must address and investigate," EU foreign ministers said in a statement.

The call came after Iran's supreme leader Ayatollah Ali Khamenei ordered a high-level clerical panel, the Guardian Council, to look into charges by pro-reform candidate Mir Hossein Mousavi, who has said he is the rightful winner of Friday's presidential election.

The EU said it was concerned over election fraud allegations and the postelection violence that erupted after the release of results.

"It is essential that the aspirations of the Iranian people are achieved through peaceful means and that freedom of expression is respected," the ministers said.

EU External Relations Commissioner Benita Ferrero-Waldner said she hoped election authorities "really look into all the complaints of irregularities."

French Foreign Minister Bernard Kouchner said the probe needs "to answer the allegations and protests made" by demonstrators.

British Foreign Secretary David Miliband said protests and the crackdown in Iran raised "very serious doubts ... about the free and fair nature" of the elections.

The EU ministers also said they remained open to relaunching talks over Iran's nuclear program with Tehran despite the concerns over the elections.

Javier Solana, the EU's foreign policy chief said he hoped to soon "engage with the leaders of Iran" over the nuclear program, which the 27-nation EU and the United States fears is being used to develop atomic weapons.

The ministers urged Iran to "act urgently on its responsibilities and obligations" on the issue.