US says `major issues` remain in Iran nuclear talks

Vienna: "Major issues" must still be resolved in talks between world powers and Iran on a nuclear deal, a US official said Sunday following signs that an agreement may be close.

"We have never speculated about the timing of anything during these negotiations, and we`re certainly not going to start now -- especially given the fact that major issues remain to be resolved in these talks," the senior State Department official said.

Iranian diplomat Alireza Miryousefi, writing on Twitter, quoted a senior official from Tehran as saying a deal by Sunday night was "logistically impossible" as the agreement being drawn up spanned 100 pages.

The so-called P5+1 group -- Britain, China, France, Germany, Russia and the United States -- faces a Monday deadline to reach a deal to end a 13-year standoff with the Islamic republic, which is seeking relief from crippling sanctions.

The talks are aimed at finalising a deal to make it extremely difficult for Iran to develop nuclear weapons.

Tehran denies its nuclear programme has military aims.