Israel has been left fuming as rapidly progressing talks in Geneva have taken Iran to the verge of sealing a deal with six major powers, which will potentially bring an end to its decade-long nuclear standoff with the West.

Reports suggest Israeli officials are slightly taken aback at the swiftness of the US diplomatic action in the last few days to push through negotiations with Iran.

US President Barack Obama's telephone call to Israeli Prime Minister Benjamin Netanyahu has done little to pacify the latter's visible exasperation. Netanyahu criticised any potential agreement with Iran and said it will not tie Israel's hands.

Calling Israel's harsh stance on Iran as "premature", the White House said in a statement: "The President provided the Prime Minister with an update on negotiations in Geneva and underscored his strong commitment to preventing Iran from obtaining a nuclear weapon, which is the aim of the ongoing negotiations. The President and Prime Minister agreed to continue to stay in touch on this issue."

The negotiations at Geneva are swiftly gaining momentum while the unscheduled eleventh-hour visits by major powers' top policymakers send positive signals about a deal. The decade-long impasse between Iran and the Western world over Tehran's nuclear ambitions has undergone a seismic shift over the last few weeks with both sides pressing ahead for negotiations.

Russia's Foreign Minister Sergei Lavrov is likely to join his counterparts during the ongoing talks on the third day. US Secretary of State John Kerry, French Foreign Minister Laurent Fabius, UK Foreign Secretary William Hague and German Foreign Minister Guido Westerwelle and European Union foreign policy chief Catherine Ashton are already negotiating with the Iranian delegation led by Tehran's Foreign Minister Mohammad Javad Zarif.

"We are reaching a very critical important point. The negotiations have reached its critical, very sensitive situation, and it needs decisions at higher levels," Zarif told about the arrival of top officials.

While the contents of the draft are still unclear, reports suggest Iran continues to call for lifting the sanctions while remaining persistent on its enrichment activities.

Upon his arrival, Kerry told reporters: "I want to emphasise there is not an agreement at this point. We hope to try to narrow these differences but I don't think anybody should mistake there are some important gaps that have to be closed."