The EU said that the general elections in Iran -- the preliminary results of which showed conservatives loyal to President Ahmadinejad set to win two-thirds of the seats in parliament -- were "neither fair for free."
Conservatives are set to win 71 percent of the seats in parliament, said the interior minister
The EU "expresses its deep concern that election procedures in the Islamic Republic of Iran have fallen below the international standards and that the electoral process did not allow for truly competitive elections," a statement said.
"In this regard it expresses its deep regret and disappointment that over a third of prospective candidates were prevented from standing in this year's parliamentary elections," the EU's Slovenian presidency said.
"These exclusions prevented the Iranian people from being able to choose freely amongst the full range of political views in their country and represent a clear violation of the international norms."
"As a result, the election was neither fair nor free."
The EU is concerned about the legitimacy of the elections in Iran
Meanwhile, conservatives lead in the Iranian capital's constituency, whose 30 seats are some of the most politically significant in Iran's parliament, according to initial results made available on Sunday.
According state news agency ISNA, parliament Speaker Gholam-Ali Hadad-Adel, a close aide of President Mahmoud Ahmadinejad, leads the Tehran list, followed by other conservatives, most of them supporters of the president.
The only reformist candidate who could slip into the top 30 is Majid Ansari. Other reformists are considerably behind.
Iranian Interior Minister Mostafa Pur Mohammadi said on Saturday that the conservative faction had so far gained more than 70 percent of the votes in the provinces in Friday's parliamentary elections.
The lead by the conservatives was expected as they formed the majority of the candidates, after more than half of the reformist candidates were disqualified by the senate-like Guardian Council for alleged lack of loyalty to the Islamic system.
Call for reforms
Ali Larijani broke ranks with President Ahmadinejad
most prominent Ahmadinejad opponent already elected to parliament is Ali Larijani, who gained a big win in the religious city of Qom, 130 kilometres (80 miles) south of Tehran.
He represents the so-called "revisionists," a group that used to back the president but gradually grew apart from him and formed their own faction.
"The conservatives should increase the atmosphere of understanding and national unity," Larijani told journalists at a press conference in Qom on Saturday. " The results of the elections should not lead to any arrogance."
"I predict that the new legislative period will be much more effective than the current one, and give priority to national interests," the pragmatic conservative official added.
Larijani resigned last October as chief nuclear negotiator after grave differences with Ahmadinejad over the country's nuclear policies and has since then been regarded as a critic of the president, especially over economic policies which have caused high inflation.