The deal, which was signed by Presidents Masoud Pezeshkian and Vladimir Putin in January, was already ratified by Russia's State Duma last month.

It passed the Iranian parliament with 191 votes in favour, eight against and three abstentions among the 212 members present, Iran's official IRNA news agency reported.

The treaty provides for joint efforts to counter common security threats but stops short of a mutual defence agreement.

Putin has called the treaty a "breakthrough document", while Pezeshkian said it would "open a new chapter in relations".

Iran and Russia have expanded military collaboration in recent years, with Tehran accused by Kyiv and Western governments of supplying drones and missiles used in Russia's war in Ukraine.

Tehran has repeatedly denied the accusation, saying it has not sided with either party to the conflict.

Both governments are under heavy Western sanctions and have increasingly coordinated their diplomatic and economic policies.

The ratification comes after Iran held four rounds of negotiations with the United States in search of a new deal to ally Western concerns about its nuclear programme.

While both sides have agreed to continue discussions, no date or venue has been set for the next round.

On Wednesday, Foreign Minister Abbas Araghchi said Iran was still "evaluating whether or not to participate" in the next round of talks, citing what he called Washington's "irrational demands".

US officials, including Middle East envoy Steve Witkoff who represents Washington in the talks, have publicly described Iran's uranium enrichment capabilities as a red line.

Araghchi reiterated on Wednesday that Iran will continue enrichment "with or without a deal".