Iranian and western officials could start drafting a nuclear agreement as early as Friday morning, Iran's foreign minister claimed at talks in Geneva.

"I think our colleagues are ready to start drafting. I think I can we can start working on some sort of joint statement," Mohammad Javad Zarif told CNN on Thursday night, adding: "It is possible to reach an understanding about an agreement before we close these talks tomorrow evening."

Zarif was speaking after the first day of a 48-hour meeting in the city between Iran and six global powers on its nuclear programme. Western officials agreed that drafting work could begin on Friday, but cautioned there were still many difficult issues to resolve.

Iranian officials at the talks said they thought the joint statement should include the outline of an initial partial agreement, as well as spelling out the goal of a long-term accord that would include agreed limits on Iran's nuclear programme and a normalisation of relations between the sanctions-hit country and the west.

The initial, partial agreement would be aimed at buying time for diplomacy rather than arriving at a comprehensive settlement breaking the international deadlock over Iran's nuclear programme, but it would nevertheless be a historic breakthrough in a decade of diplomatic sparring marked by paralysis and distrust.

Zarif said that the drafting of a joint statement could start at a meeting on Friday morning with Catherine Ashton, the EU foreign policy chief who is acting as convenor of the six-nation group, comprising the US, UK, France, Germany, Russia and China. Ashton will hold a breakfast meeting with senior diplomats from the group before seeing Zarif.

"The issues are on the table. We have dealt with the concerns of each side, and now we need to start drafting some sort of a agreement in a joint fashion," Zarif said. "I believe the ingredients are there. It will take a lot of effort and good faith and good will. I know we have it on our side … There is a opportunity offered by the election of [Iran's moderate] President Rouhani and that it is an opportunity that has to be seized."

Asked later whether the agreement taking shape was good for Iran, Zarif's deputy, Abbas Araqchi replied: "Certainly so."

In another development, Zarif also said that Yukiya Amano, head of the International Atomic Energy Agency, would visit Tehran on Monday, raising expectations of a breakthrough in long-running talks between Iran and the IAEA aimed at clearing up uncertainty over Iran's past development work on nuclear weapons.

Zarif said: "Mr Amano's visit is going to be an important indication that we are in the process of moving forward."

The hopeful remarks followed a full meeting of all the delegates and then separate discussions between Iranian officials with the diplomats from the US, Russia and China, and one with the three European states represented, the UK, France and Germany. British and Iranian diplomats discussed the eventual appointment of non-resident charges d'affaires in each other's countries.

Zarif had cancelled a trip to Rome so that he could hold a face-to-face meeting with Ashton as it became clear that substantial progress was being made.

A senior US official, speaking before the talks began, held out the possibility of a limited relaxation of sanctions. He said: "In response to a first step agreed to by Iran that halts their [nuclear] programme from advancing further, we are prepared to offer limited, targeted, and reversible sanctions relief.

"We are not talking about touching the core architecture of the Iranian sanctions regime in this first step in any way. And if Iran does not live up to its obligations under the initial understanding, or if we cannot get a comprehensive agreement finalised, any economic relief we will have given Iran can, in fact, be reversed."

The US official added: "For the first time, Iran appears to be committed to moving this negotiation process forward quickly. One of the key shifts in the Iranian strategy we've seen with this new team is a recognition that they need to move quickly to get economic relief for their people given the political platform on which they were elected. And for the first time, we aren't seeing them use this negotiating process simply to buy time."