Iran & major world powers will extend their talks over Tehran's disputed nuclear programme until July 2015.
Talks between Iran and six powers are expected to fail to reach a deal to lift US and EU sanctions.
A senior Russian diplomat says if there’s a will in Washington & Tehran, a deal could be reached soon.
While all sides agree to keep talking, little progress has been made in overcoming significant disagreements.
The warning was issued at a board meeting of the UN’s International Atomic Energy Agency in Vienna.
The US last week penalised a number of Iranian and foreign companies for violating sanctions against Tehran.