LONDON — Iran has broken the terms of its 2015 nuclear deal and must immediately stop and reverse its activities, a spokesman for Britain's Foreign Office said on Sunday.

Iran said on Sunday it will boost its uranium enrichment in a few hours above a cap set by the nuclear deal, a move that could eventually culminate in the return of all international sanctions on Tehran.

"Iran has broken the terms of the JCPoA," the Foreign Office spokesman said, refering to the deal's formal name, the Joint Comprehensive Plan of Action (JCPOA).

"While the UK remains fully committed to the deal, Iran must immediately stop and reverse all activities inconsistent with its obligations. We are coordinating with other JCPoA participants regarding the next steps under the terms of the deal, including a Joint Commission."

Germany on Sunday urged Iran to stop taking measures that undermined the non-proliferation deal it agreed in exchange for eased sanctions after Tehran announced it would boost nuclear enrichment above agreed limits.

"We are extremely concerned at Iran's announcement that it has started uranium enrichment above the limit of 3.67%," a German foreign ministry spokesman said.

"We strongly urge Iran to stop and reverse all activities inconsistent with its commitments."

The spokesman added that Germany was in touch with other European participants in the non-proliferation deal - Britain and France - to decide on the next steps. Iran blames the U.S., which withdrew from the deal, for the latest tensions. — Reuters