A French diplomatic source told Reuters last week that European powers would have to restore UN sanctions on Iran under the so-called "snapback mechanism" if there were no nuclear deal that guaranteed European security interests.

The "snapback mechanism" is a process that would re-impose UN sanctions on Tehran under a 2015 nuclear deal that lifted the measures in return for restrictions on Iran's nuclear programme.

"The threat to use the snapback mechanism lacks legal and political basis and will be met with an appropriate and proportionate response from the Islamic Republic of Iran," Foreign Ministry Spokesperson, Esmaeil Baghaei told a press conference in Tehran, without giving further details.

The 2015 deal with Britain, Germany, France, the US, Russia and China, known as the Joint Comprehensive Plan of Action (JCPOA), states that if the parties cannot resolve accusations of "significant non-performance" by Iran, the "snapback mechanism" process can be triggered by the 15-member UN Security Council.

Trump, whose second presidency began in January, has urged Tehran to return to nuclear negotiations on a new deal after a ceasefire was reached last month that ended a 12-day air war between Iran and Israel that destabilised the Middle East.

--Reuters--