Iran and six major powers have so far not discussed extending negotiations on a nuclear agreement despite the fact that their deadline is a week away, a senior American official said on Monday, according to Reuters.

Senior foreign officials from Iran and the six powers – the United States, Britain, France, Germany, Russia and China – gather in Vienna this week for the last round of negotiations before a November 24 deadline to reach an accord that would end sanctions in exchange for curbs on Tehran’s atomic program.

“We have continued to make some progress in the course of these negotiations but we still have gaps to close and we do not yet know if we will be able to do so,” the official told reporters on condition of anonymity.

“Extension (of the negotiations) is not and has not been a subject of negotiations at this point,” the official added.

The senior U.S. official denied media reports that the United States had given Iran an eight-page proposal at recent talks in Oman, saying, “There was not a piece of paper that the Iranians walked away with.”

Another senior Western diplomat said: “The negotiations are hardly progressing … The Iranians are not moving an inch. We’re 10 days before the end of talks … We’re still very far apart.”

Despite assurances it is confident of reaching a deal by the November 24 deadline, Iran has been toughening its stance in recent weeks. Iran’s chief negotiator, Abbas Araqchi, recently said he sees no prospect for a deal unless the other side abandons its “illogical excessive demands”.

A senior Iranian official followed those comments by declaring that Iran will demand that all Western sanctions be lifted as part of a final deal, rejecting an American proposal of a gradual lifting of sanctions.

U.S. President Barack Obama admitted last week that there was a “big gap” between Iran and the six world powers, telling CBS News, “We may not be able to get there”.