Iran conservative lawmakers, who control a majority in Iran's parliament, on Tuesday introduced a bill which would force the government to resume uranium enrichment and halt snap UN inspections of nuclear facilities.
The official IRNA news agency said lawmakers want to give the bill a "double urgency" status, meaning it could be discussed in parliament in the next few days.
If approved, the bill would bring Tehran into direct conflict with the United Nations' nuclear watchdog which has given Iran until late November to halt all uranium enrichment activities or face being reported to the UN Security Council.
Government officials have said they would have no choice but to obey such a bill if approved by parliament. But diplomats believe Iran is using parliament as a bargaining tool ahead of key negotiations on its nuclear programme this week.
"They want us to think that we need to go easy on them or the hard-liners in parliament will gain the upper hand," one diplomat said. "Ultimately, parliament will do what the (Iranian) leadership wants it to do, not vice versa."
Iran last year agreed to temporarily halt enriching uranium - which can produce bomb-grade material - and agreed to snap inspections of its nuclear facilities in a bid to counter US-led charges that it has a covert nuclear arms programme.
Iran says its nuclear programme is solely aimed at generating electricity to meet booming demand.
"From the day the bill is approved the government would be obliged to stop the suspension of uranium enrichment as well as the temporary implementation of the additional protocol (on snap inspections)," lawmaker Rafat Bayat told IRNA.
She said the bill had been submitted with support signatures from 93 of parliament's 290 deputies.
The proposed bill comes as Iranian officials prepared to meet with negotiators from Britain, Germany and France in Vienna to discuss a possible deal to keep Iran's case from being sent to the Security Council.