Iran's foreign minister said Monday he believed there should be no further extension to nuclear talks with major powers but he would negotiate "as long as necessary".

"I always believe there shouldn't be any extension but we could work as long as necessary to finish this," Mohammad Javad Zarif said in English as he met his Chinese counterpart Wang Yi in Vienna.

Several deadlines have been missed over the more than two weeks of talks between Iran to nail down a historic deal curbing Iran's nuclear programme in exchange for sanctions relief.

On Monday the terms of a 2013 interim deal freezing parts of Iran's nuclear programme in return for minor sanctions relief were due to expire, although this has been extended several times already.

With the foreign ministers of all six powers except Britain gathered in Vienna on a 17th day of talks, there was hope Monday that a deal may be finally be in sight.

Iran's President Hassan Rouhani will address the nation on state television at 10:00 pm (1730 GMT), the culture ministry in a notice sent to media outlets in Iran.