A senior Russian official has suggested that Iran and six world powers are close to a nuclear agreement as negotiations in Switzerland were adjourned to allow members of the Iranian delegation to attend the funeral of their president's mother.

Sergey Ryabkov, Russia deputy foreign minister, told the AP news agency on Friday that while some issues remain, negotiators were expected to "finish their main work" before the talks in Lausanne resume next week.

Rybakov spoke shortly before US Secretary of State John Kerry wrapped up five days of meetings in the Swiss city with Iranian Foreign Minister Mohammad Javad Zarif.

Speaking to Al Jazeera, US State Department spokeswoman Marie Harf said that "all of the issues were still being worked through" and the US was hopeful of making "some progress".

"We are closer to an agreement today than we were yesterday," Harf said, adding that the onus was on Iran and it had some "big decisions to make".

The negotiations had been tentatively extended to go into Saturday but the Iranian delegation decided to depart for home later on Friday to allow negotiators, including Zarif and Hossein Fereydoon, a brother of Iranian President Hassan Rouhani, to attend the funeral of Rouhani's mother.

Iran's ISNA news agency said talks would resume Wednesday.

Ryabkov's comments tally with those of other officials who told AP earlier that the US and Iran are drafting elements of a deal that commits Tehran to a 40 percent cut in the number of machines it could use to make an atomic bomb.

In return, the Iranians would get quick relief from some of the crippling economic sanctions currently imposed on the country and a partial lift of a UN embargo on conventional arms.

Agreement on those details of Iran's uranium enrichment program could signal a breakthrough for a larger deal aimed at containing the Islamic Republic's nuclear activities.

There is a March 31 deadline to reach a preliminary deal while negotiators ultimately want to reach a full agreement by the end of June.

EU talks

In Brussels on Friday, EU foreign affairs head Federica Mogherini held talks with British, French and German leaders to discuss ongoing negotiations on Iran's contested nuclear programme, her office said.

British Prime Minister David Cameron, French President Francois Hollande and German Chancellor Angela Merkel discussed the state of negotiations in a brief meeting.

"The meeting was to take stock of the situation so as to have a clear, coordinated European position as March 31 nears," a spokeswoman said.

The talks between the five UN permanent Security Council members - Britain, China, France, Russia and the US - plus Germany and Iran, began in late 2013 after Iran accepted initial limits on its nuclear programme in return for an easing of some of the damaging economic sanctions imposed by the West.

The Islamic Republic insists its nuclear programme is purely for peaceful civilian purposes.

Source: Al Jazeera and agencies