TEHRAN (Tasnim) � It would be a strategic mistake for Iran to agree on a final deal over its nuclear energy program if the US refuses to sign the deal, an Iranian political analyst said.

There have been multiple cases in the past where the US breached what it had signed, so Washington will "undoubtedly" lack commitment if it is not going to sign a possible nuclear deal on Iran's nuclear program, Foad Izadi told Tasnim on Sunday.

He made the comments in reaction to speculation that the US could decide not to sign a possible final nuclear deal between Iran and the Group 5+1 (Russia, China, the US, Britain, France and Germany).

"(Accepting) a deal without the US signature will be a big strategic mistake for Iran," Izadi said.

"If the Americans are not supposed to sign the agreement, the question is what did we work hard for over the past 2 years? Of what legal value will be an agreement that would not be binding for the US?" he asked.

His comments come as Iran and the Group 5+1 (alternatively known as P5+1 or E3+3) are busy negotiating in the Austrian capital to clinch a lasting nuclear deal.

The two sides have been negotiating over the past 22 months to end more than a decade of standoff over Tehran's civilian nuclear program once and for all.

On Tuesday, Iran and the sextet gave themselves an extra week beyond an end-June deadline to nail down details of the long-awaited accord.

By Tasnim News Agency