There were heated exchanges on Monday as the MPs, whose mandate ends in May, blasted on Friday's polls as rigged and accused hardliners of seeking to impose an Islam similar to that of Afghanistan's ousted Taliban.
"I resign," said female reformist MP Fatemeh Haghighatjou, "because a staged, unfair and uncompetitive election was held with the aim of yielding an obedient Majlis (parliament)."
"They do not want a republic, but a Taliban-style Islam," she charged.
More than 80 incumbent deputies in the reformist held parliament, were disqualified from standing in Friday's polls by the Guardians Council, an unelected 12-member political watchdog run by hardliners.
Haghighatjou was one of 120 MPs who quit before the polls, but under parliamentary procedure each resignation has to be debated and approved by the assembly.
Official results show conservatives have so far won 129 of
parliament's 290 seats compared to 40 won by reformists.
Independents won 30 seats, five places are reserved for the
Christian, Jewish and Zoroastrian minorities and votes for the
30 Tehran seats are still being counted. The poll was postponed in Bam due to December's earthquake and 55 seats are to be recontested because no candidate got more than 25% of the vote.
Two women were among 14 conservatives who already have
enough votes in Tehran to be elected, with 2600 of more than 3700 ballot boxes still to be counted. There were 13 women MPs in the last parliament.
Hossien Ansari-Rad, another reformist MP, said there was no point in deputies tackling any pending legislation - such as the national budget - given that they were deemed unsuitable to stand in the polls.
"I resign, because a staged, unfair and uncompetitive election was held with the aim of yielding an obedient Majlis (parliament). They do not want a republic, but a Taliban-style Islam."
The Guardians Council, which drew the blacklist, also screens all legislation passed by the Majlis.
"Since the Guardians Council disqualified some 77 of incumbent MPs, whatever laws that the current Majlis approves will be rejected, so why are they insisting on approving the budget law?" he asked.
The angry session was carried live on state radio.
Another reformist MP, Muhammad Kianoush-Rad, said the 50.57% turnout - an all-time low for a parliamentary poll in the 25-year history of the Islamic republic - showed a "deepening of the current gap between the people and the regime."
And Bahaodin Adab, an ethnic Kurdish MP, spoke of reformists
being targeted by increasing threats.
"We are getting threatening phone calls home to our families, so are you expecting us to come here sit and discuss the budget?" He told Majlis speaker Mehdi Karoubi that outgoing deputies "have no security."
Scuffles erupted after a conservative MP, Ghodratollah Alikhani, said the reformists only had themselves to blame for losing. "You the reformists did this to yourself, to the reform movement and to (President Muhammad) Khatami," he asserted.
EU's 'deep regret'
The turnout in Friday's elections
Also on Monday, EU foreign ministers expressed "deep regret" after Iranian elections from which most reformist candidates were barred.
The ministers voiced their "deep regret and disappointment that a large number of candidates were prevented from standing, thus making a genuine democratic choice by the Iranian people impossible," according to a draft statement on Monday.
"This interference was a setback for the democratic process in Iran," the statement added, cited by diplomats attending regular ministerial talks in Brussels.
The European Union has been pursuing a twin-track dialogue with Iran based on trade and human rights issues. But the talks have been on hold since June because of EU concerns about Iran's nuclear ambitions.
"(We express) deep regret and disappointment that a large number of candidates were prevented from standing, thus making a genuine democratic choice by the Iranian people impossible."
One diplomat said the statement, set to be agreed by ministers, amounted to a severe slap to Tehran, while stopping short of completely rejecting the polls. "It is being critical but the outcome has not been questioned," he said.
"The EU is making clear its disappointment," he added. Another noted that the EU had set four areas where it wanted progress from Iran: human rights; nuclear concerns; the fight against terrorism and support in the Middle East process.
"This is one of those key factors, it is very important when deciding if you are going to reach a trade agreement with someone," he added.