The United States and Iran have begun a third round of nuclear talks, entering what experts describe as a more difficult phase of technical negotiations this weekend as Washington lays out its conditions.

Israeli Prime Minister Benjamin Netanyahu on Sunday repeated calls for Iran's entire nuclear infrastructure to be dismantled, as Washington and Tehran engage in talks for a nuclear accord.

Washington opposes Tehran’s insistence on retaining the ability to enrich uranium, as the two sides meet in Oman for a third round of negotiations.