Iran will take reciprocal measures in response to any breach of this year's nuclear deal, the Foreign Ministry warned on Monday, after Tehran said new U.S. visa restrictions contravened the historic agreement.

Iran has started to restrict its nuclear programme under the terms of the July 14 deal with six world powers, including the United States. When the restrictions are completed, international sanctions on Tehran will be lifted.

But decades-old mistrust between Tehran and Washington is as high as ever, and each side has accused the other of undermining the pact, known as the Joint Comprehensive Plan of Action (JCPOA).

Earlier this month, the U.S. Congress passed a law restricting visa-free travel rights for people who have visited Iran or hold dual Iranian nationality, a measure that Iran's foreign minister called a breach of the deal.

The measure, which affects citizens of the 38 mostly European countries that have visa waiver arrangements with the United States, is framed as a counterterrorism measure and also targets Iraq, Syria and Sudan.

"Any steps taken outside the agreement are unacceptable to Iran, and Iran will take its own steps in response where necessary," Foreign Ministry spokesman Hossein Jaberi Ansari told a televised news conference when asked about the U.S. law.

He said a committee tasked with overseeing the deal would be responsible for ordering the Iranian response to any breaches. Nuclear negotiator Abbas Araqchi, who heads that committee, has also said the visa law contravenes the deal.

VISA LAW

European Union countries have criticised the visa law, which was introduced after a series of Islamist attacks by citizens of Western countries who had been radicalised abroad. U.S. officials say Iran is included because Washington designates it a "state sponsor of terrorism", along with Syria and Sudan.

Tehran says it has nothing to do with the recent attacks and is fighting the group that inspired them, Islamic State.

Iran's hardline Revolutionary Guards have also been pushing the boundaries of the deal, most notably by test-firing a ballistic missile capable of carrying a nuclear warhead in breach of a U.N. Security Council resolution.

By Reuters