German Chancellor Olaf Scholz delivers his first government statement at the Reichstag building in Berlin Dec. 15, 2021, after he was elected as the new federal chancellor Dec. 8.(Photo:Xinhua)

The chances of reviving the Iran nuclear accord are dwindling and the "moment of truth" has arrived for Tehran's leadership, German Chancellor Olaf Scholz said Saturday.

"We now have the chance to reach an agreement that will allow sanctions to be lifted. But if we do not succeed very quickly, the negotiations risk failing," Scholz told the Munich Security Conference. "The Iranian leadership has a choice. Now is the moment of truth."

Iranian Foreign Minister Hossein Amir Abdollahian, speaking at the same Munich gathering, said his country was "ready to achieve a good deal at the earliest possible time if the other side makes the needed political decision."

"We are very serious," he added, speaking through an interpreter.

The 2015 Iran nuclear agreement had offered Tehran sanctions relief in exchange for curbs on its nuclear program, but the US unilaterally withdrew in 2018 under then-president Donald Trump and reimposed heavy economic sanctions.

This in turn prompted Iran to start ramping up its nuclear activities.

The outline of a new deal appears to be on the table in talks which have been held in Vienna since late November between signatories Britain, China, France, Germany, Russia - and the US indirectly.

Iran's top diplomat said the Western countries need to show "flexibility" in the talks.

"If at this level, the Western sides don't do what needs to be done by them in practice, then they should be held responsible for the failure of the talks," he said in Munich.

AFP