In a letter addressed to President Ebrahim Raisi and read at parliament, 250 MPs out of the 290-strong assembly, set out several conditions for reaching a deal.

It came amid growing signs over the weekend that a deal could be struck between Iran and world powers, including the United States.

German Chancellor Olaf Scholz said on Saturday that the "moment of truth" has arrived for Tehran's leadership.

And on Sunday Israeli Prime Minister Naftali Bennett said Iran may "shortly" agree a new nuclear deal with major powers.

In the letter, the Iranian MPs insisted that the United States, France, Germany and Britain must guarantee they would not withdraw from a new deal.

The Vienna talks aim to revive the 2015 accord known formally as the Joint Comprehensive Plan of Action (JCPOA).

The deal offered Iran sanctions relief in exchange for curbs on its nuclear programme, but the US unilaterally withdrew from it in 2018 under then-president Donald Trump and reimposed heavy economic sanctions.

This in turn prompted Iran to begin rolling back on its commitments.

The MPs also demanded a pledge from the US and other parties to the JCPOA that they would not use a "snapback" mechanism that would reimpose sanctions on Iran in case Tehran violates its part of the deal.

"We have to learn a lesson from past experiences... by not committing to any agreement without obtaining the necessary guarantees first," the MPs said, according to state news agency IRNA.

They said Western powers must first fulfil their obligations by lifting the sanctions -- especially the ones imposed on Iranian oil and banks -- adding that once Tehran has verified that it will in turn fulfil its obligations.

The MPs also said a return to the deal should only take place if all sanctions, including on missile technology and human rights, are lifted.

Since November, Iran has been engaged in direct talks in Vienna with Britain, China, France, Germany and Russia directly and indirectly with the United States.