LONDON (Reuters) - Iran believes new sanctions that the United States has imposed on it breach the nuclear deal it agreed in 2015 and has complained to a body that oversees the pact’s implementation, a senior politician said on Tuesday.

Slideshow ( 2 images )

Under the Joint Comprehensive Plan of Action (JCPOA), signed by the United States, Russia, China and three European powers, Iran curbed its nuclear work in return for the lifting of most sanctions.

However, the U.S. Treasury imposed sanctions on six Iranian firms in late July for their role in the development of a ballistic missile program, after Tehran launched a rocket capable of putting a satellite into orbit.

The U.S. Senate voted on the same day to impose new sanctions on Iran, Russia and North Korea. The sanctions in that bill also target Iran’s missile programs as well as human rights abuses.

“Iran’s JCPOA supervisory body assessed the new U.S. sanctions and decided that they contradict parts of the nuclear deal,” Ali Larijani, the speaker of Iran’s parliament, was quoted as saying by the Tasnim news agency.

“Iran has complained to the (JCPOA) Commission for the breach of the deal by America,” he added, referring to the joint commission set up by the six world powers, Iran and the European Union to handle any complaints about the deal’s implementation.

If the commission is unable to resolve a dispute, parties can take their grievances to the U.N. Security Council.

U.S. President Donald Trump, who has called the agreement - negotiated by his predecessor Barack Obama - “the worst deal ever” last week told Iran to adhere to the terms of the nuclear accord or face “big, big problems”, although his administration has certified Iran as being in compliance with the it.

Iranian media said on Monday the government had agreed measures in response to the U.S. sanctions and that President Hassan Rouhani would announce them soon to relevant ministries.

Iran has previously accused the United States of defying the spirit of the nuclear deal or “showing bad faith”, but has not taken any formal action against Washington.