The head of Iran's Atomic Energy Organization, Ali Akbar Salehi, told lawmakers on Sunday that Iran will restart activities at the Arak heavy water nuclear reactor, the ISNA news agency reported.
ISNA cited a member of parliament who attended the meeting. Heavy water can be employed in reactors to produce plutonium, a fuel used in nuclear warheads.
In May Iran announced planned measures to breach the nuclear agreement with major world powers following the U.S. withdrawal from deal and Washington's reimposition of tough sanctions.
On July 3, President Hassan Rouhani said Tehran would increase its uranium enrichment levels and start to revive its Arak heavy-water reactor after July 7 if the nations in the nuclear pact did not protect trade with Iran promised under the deal but blocked by the U.S. sanctions.
The presence of foreign forces would be the main source of tension in the Gulf, said on Sunday in a meeting with Oman's foreign minister in Tehran, according to the official presidency website.
France, Italy and Denmark gave initial support for a British plan for a European-led naval mission to ensure safe shipping through the Strait of Hormuz, proposed after Iran's seizure of a British-flagged tanker, three senior EU diplomats said last week.
"The presence of foreign forces will not only not help the security of the region, but will be the main factor for tension," Rouhani said, saying Iran and Oman had primary responsibility for securing the Strait of Hormuz. "The roots of the unpleasant events and tension in the region today are the unilateral withdrawal of America (from the 2015 nuclear deal)," he said.
Britain's seizure of an Iranian oil tanker in Gibraltar is a violation of the 2015 nuclear deal, Abbas Araqchi, a senior member of the team who negotiated the deal and a deputy foreign minister, said on Sunday, according to the ISNA news agency.
"We witnessed the seizure of an oil tanker carrying Iranian oil in the Strait of Gibraltar which in our view is a violation of (the nuclear deal)," Araqchi said. "And the countries who are part of (the nuclear deal) shouldn't create obstacles for the export of Iranian oil."