Britain, France, and Germany said that "EU and UK sanctions will be maintained," according to a statement from the British foreign ministry released on Thursday.

The series of British, EU and US sanctions "on individuals and entities involved in Iran's missile, nuclear, and other weapons programmes" were supposed to be lifted on October 18, the ministry said.

The deal agreed with world powers in 2015 was aimed at curbing Iran's nuclear programme in exchange for the lifting of international sanctions.

But the accord began unravelling in 2018 when then US president Donald Trump unilaterally withdrew from it and began reimposing sanctions and Iran retaliated by dropping some of its obligations under the agreement.

Iran's foreign ministry said it considers "the decision of the EU and three European countries as an illegal act with malicious intentions, and contrary to their obligations under the nuclear agreement".

"We warn the European parties against taking actions that will certainly complicate the management of their relations and have a negative impact on... negotiations for the lifting of sanctions," it said in a statement issued late Thursday.

Efforts to revive the deal have been fruitless so far with European-led talks on hold since 2022.

In its statement, the British foreign ministry said the decision to keep the sanctions in place had been based on "continued Iranian non-compliance with their... commitments and ongoing nuclear escalation".