Obama urges Iran to grab 'historic chance' for n-deal

US President Barack Obama called on Iranian leaders not to miss a "historic opportunity" to reach a reasonable nuclear deal, saying such a moment "may not come again soon".

In a video message to mark Nowruz (Persian New Year), Obama on Thursday said this is "the best opportunity in decades to pursue a different future between our countries," referring to the ongoing talks being held in Switzerland to clinch a deal on Iran's nuclear programme, Xinhua reported.

Obama said "gaps remain", despite the progress made in the negotiations between Iran and six major countries, or P5+1, which includes the US, Britain, China, France, Russia and Germany.

"The days and weeks ahead would be critical. Our negotiations have made progress, but gaps remain. And there are people, in both our countries and beyond, who oppose a diplomatic resolution," he said.

Obama added that Iran and the US both kept their commitments to an interim deal reached a year ago, under which Iran halted progress on its nuclear programme in exchange for the easing of economic sanctions imposed by the US-led West.

The US suspects that Iran's nuclear programme is aimed at producing a nuclear bomb that could threaten the existence of Israel, the sole US ally in the Middle East, but Tehran has insisted that its programme is solely for the peaceful use of nuclear energy.

If Iran agrees to take "meaningful, verifiable steps" to reach a reasonable deal that will assure the peaceful nature of its nuclear programme, it would open the door to a brighter future for Iranian people. Otherwise, Iran will keep on the current path of isolation and hardship, Obama said.

"This is what's at stake today. And this moment may not come again soon. I believe that our nations have an historic opportunity to resolve this issue peacefully - an opportunity we should not miss," Obama said.

Iran and the P5+1 group are intensifying their negotiations this week in the Swiss city of Lausanne, in an attempt to reach a comprehensive framework deal before the end of March.