Iran on Sunday condemned as "unjustifiable" the reinstatement of United Nations sanctions over its nuclear programme, after the collapse of talks with Western powers and Israeli and US strikes on its nuclear sites.

The measures, which bar dealings linked to the Islamic republic's nuclear and ballistic missile activities, took effect overnight after Western powers triggered the so-called "snapback" mechanism under the 2015 nuclear accord.

"The reactivation of annulled resolutions is legally baseless and unjustifiable... all countries must refrain from recognising this illegal situation," the Iranian foreign ministry said in a statement.

"The Islamic Republic of Iran will firmly defend its national rights and interests, and any action aimed at undermining the rights and interests of its people will face a firm and appropriate response," it added.

The return of the sanctions ends months of tense diplomacy aimed at reviving nuclear talks derailed since June, when Israeli and US forces bombed Iranian nuclear facilities.

Despite the reimposition, Western leaders stressed channels for dialogue remained open.

Kaja Kallas, the European Union's top diplomat, on Sunday said the reimposition of sanctions "must not be the end of diplomacy",........

© International Business Times