Iran's hardline dominated parliament says it has received a draft bill which could oblige the government in Tehran to resume uranium enrichment.
Iran denies claims that it wants to build nuclear weapons
The bill would also stop international inspection of its nuclear sites.
This comes a day ahead of a meeting between Iranian and European officials to discuss a compromise formula for Iran's nuclear programme.
So far the bill is only said to have 93 signatures, which is not enough to pass in parliament.
And it still has to be formally announced in parliament before it can be tabled for debate.
Meanwhile, a member of parliament's presiding board has said another bill could be debated as soon as Sunday, urging the government to obtain peaceful nuclear technology, including mastering the fuel cycle.
This is said to have received more than 200 signatures some weeks ago but now 50 MPs have asked for the debate to be brought forward in the light of the current negotiations with the Europeans on the nuclear issue.
The measures could be attempts by hardline parliamentarians to scupper what they fear might be an imminent deal with the Europeans.
Or it could be a way of showing Europe what pressure the Iranian government is under domestically from hardliners - in the hope of winning more concessions.