World powers and Iran are working intensively to advance talks in Geneva over Iran's disputed nuclear programme, a spokesman for the European Union foreign policy chief, Catherine Ashton, said.
"Very intense work is continuing," the spokesman, Michael Mann, told reporters on Friday. "We hope to make progress today."
The so-called P5+1 - the United States, Russia, China, France, Britain and Germany - appeared to be closing in on a long-elusive deal in the decade-old dispute over Iranian nuclear intentions after talks on Thursday.
Russian Foreign Minister Sergey Lavrov said that world powers and Iran could agree on a "road map" for ending the dispute over Tehran's nuclear programme.
He told that reporters he did not wish to pre-judge the outcome of the talks, but said Iran should be allowed to have a peaceful nuclear programme under the watch of the International Atomic Energy Agency.
Western powers suspect Iran's uranium enrichment may be aimed at developing nuclear weapons, a claim Tehran denies.
US Secretary of State John Kerry arrived in Geneva on Friday in a bid to help secure the deal. Kerry, who along with his French, British and German counterparts announced at the last minute he would be joining the ongoing negotiations, arrived in the Swiss city at about 1400 GMT.
Kerry said there remained unresolved issues in the talks, important gaps that needed to be closed and that there was no agreement so far.
The US Secretary of State said he would meet Iran Foreign Minister Zarif to narrow differences.
Kerry, who was in Amman on Thursday, met Israeli Prime Minister Benjamin Netanyahu in Tel Aviv earlier on Friday, and his surprise decision to go to Geneva was expected to infuriate key US ally, Israel.
There is a window of opportunity now that has been created by the Iranian people... and that opportunity needs to be seized.
Speaking as he headed into the meeting with Kerry, Netanyahu said that Iran had got "the deal of the century".
"I understand that the Iranians are walking around very satisfied in Geneva, as well they should be, because they got everything (they wanted) and paid nothing," he said.
"They wanted relief from sanctions after years of a gruelling sanctions regime. They got that. They are paying nothing because they are not reducing in any way their nuclear enrichment capability."
The meeting is the second since Iran's president Hassan Rouhani took office in August pledging to resolve the nuclear dispute and lift sanctions by engaging with world powers.
"There is a window of opportunity now that has been created by the Iranian people... and that opportunity needs to be seized," Iran's Foreign Minister Mohammad Javad Zarif said.
French Foreign Minister Laurent Fabius will also attend the international talks, his ministry announced on Friday, further fuelling speculation that a historic agreement may be in sight.
The six global powers are unlikely to agree on anything less than a suspension of enrichment of uranium to 20 percent fissile purity, a level that constitutes a technical milestone not far from the threshold for a nuclear warhead.