Washington, April 2 (IANS): The US said on Wednesday that the Iran nuclear talks underway in Switzerland that are aimed at laying the groundwork for a potentially historic agreement have been "productive" and making "progress".

"The sense that we have is that, yes, the talks continue to be productive and that progress is being made," White House spokesman Josh Earnest said on Wednesday, according to a Press TV report.

He added that "as long as we are in a position of convening serious talks that are making progress", Washington "would not arbitrarily or abruptly end them".

"But, if we are in a situation where we sense that the talks have stalled then yes, the US and the international community is prepared to walk away," Earnest stated.

Representatives from Iran and the P5 1 group of world powers -- the US, Britain, China, France, Russia, plus Germany -- along with senior European Union (EU) officials have been holding marathon negotiations in the Swiss city of Lausanne to narrow down differences in order to reach a comprehensive deal on Tehran's nuclear programme.

The negotiators had missed the March 31 deadline for reaching a mutual understanding over the "tricky issues" hindering the framework understanding, but they have decided to continue the talks to break the impasse.

The potential agreement would pave the way for a much broader deal before July 1, which would guarantee the civilian nature of Iran's nuclear programme in return for a promise by the international powers to lift the sanctions imposed on Iran.

However, a senior Iranian negotiator has said that any nuclear deal with the P5 1 countries should guarantee the removal of all sanctions.