Top Iranian and U.S. negotiators began a new round of indirect talks on Saturday to hammer out a deal curbing Tehran's nuclear programme, while U.S. President Donald Trump signalled confidence in clinching a new pact that would block Iran's path to a nuclear bomb.

The United States and Iran are set to begin a third round of nuclear talks this weekend, entering what experts describe as a more difficult phase of technical negotiations as Washington lays out stricter conditions.