The move quickly exposed tension between President Hassan Rouhani’s government and lawmakers in Tehran, where hardliners routinely voice doubts about the merit of talking to the West.
Rouhani’s spokesman said the bill, which still has to be signed into law by Iran’s Guardian Council, was unconstitutional.
The action in parliament, just one week before the nuclear deal deadline, is unlikely to immediately affect those talks but it could prove a complication after an accord is signed because the bill lays down terms for MPs’ accepting its terms.
Rouhani, a moderate who aims to end Iran’s diplomatic isolation, wants a deal to ensure the lifting of sanctions that have hobbled the economy.
However critics of his nuclear policy, including members of the conservative-dominated legislature, say too many concessions have been made.
The bill says the government must “preserve the country’s nuclear rights and achievements,” a reference to retaining the ability to enrich uranium and continuing to keep all its nuclear facilities open.
Such demands have already been enshrined in an outline agreement struck on April 2 between Iran and the P5+1 powers — Britain, China, France, Russia and the United States plus Germany.
But the bill, whose backers said it would protect Iran’s negotiating team from further demands, goes further and says sanctions must be lifted “on the day Iran starts implementing its obligations.”
The timing of removal has become important as members of the P5+1 have said it can only happen upon international verification that Iran has met requirements laid down under a deal.
Some 214 lawmakers out of 244 present supported the bill, with 10 against, six abstentions and the remainder not voting.
Bargaining stepped up
Bargaining over a final deal, due by June 30, intensified on Monday when Britain and France reiterated that comprehensive inspections of Iran’s nuclear facilities are essential.
The bill passed in Tehran allows inspections of nuclear sites but not military or sensitive non-nuclear establishments — a refusal likely to alarm Western powers given their longstanding suspicion Iran is covertly developing an atomic bomb.
Rouhani’s spokesman, Mohammad Bagher Nobakht, said the draft law infringed the country’s defence and security policies.
“This bill contradicts article 176 of the constitution. The issue of negotiations is in the sphere of the Supreme National Security Council… not the government or the parliament,” he said.
His comments came despite the bill being watered down on Sunday, with the task of supervising a nuclear deal being given to the SNSC, a committee ultimately controlled by Iran’s supreme leader Ayatollah Ali Khamenei.
Although parliament will still have to approve a nuclear deal it had wanted the right to have formal oversight.
Roadblocks to an accord remain on both its details and opposition to its measures from both US and Iranian lawmakers.
In a measure similar to that taken in Tehran, President Barack Obama has given US lawmakers 30 days to review any nuclear deal.
Obama, a Democrat, has faced persistent opposition to his outreach to Iran from Congress, which is controlled by Republicans, who by their right of review may try to block an agreement.
Other critics of the nuclear diplomacy include Israel’s Prime Minister Benjamin Netanyahu who warned Congress in March against signing “a bad deal.”
The speaker of Iran’s parliament, Ali Larijani, has said its members will not stand in the way if Khamenei, who has the last word on all matters foreign and domestic, says an agreement is in the national interest.
Iran has for years been faced with UN, EU and US sanctions that have placed crippling restrictions on the country’s oil and banking sectors, trade and everyday life for the 78 million population.
Iran denies its nuclear program has military objectives, insisting it is for purely peaceful energy development.