Iran says progress has been made at talks on its nuclear programme with diplomats from western Europe.
Iran denies claims that it wants to build nuclear weapons
A senior Iranian negotiator Hossein Mousavian said: "If the discussions continue like this, there is a possibility we will reach a solution."
But there has been no official comment so far from the UK, French and German envoys taking part in the Paris talks.
The European powers have threatened to refer Iran to the UN Security Council unless it halts uranium enrichment.
After seven hours of talks Mr Mousavian described as "very delicate" and "complicated", discussions were still going on. It is thought they might spill into Saturday.
Officials would not comment on the substance of the talks, but it is understood Iran may be offered nuclear fuel and promised increased trade if it stops its enrichment activities.
Diplomats said Iran was offering a six-month suspension of enrichment, while the European trio want an indefinite moratorium, according to Reuters.
EU leaders in Brussels reiterated on Friday that a "full and sustained suspension of all enrichment and reprocessing activities... would open the door for talks on long-term cooperation offering mutual benefits".
Europe and the US fear Iran could be planning to use enriched uranium to build a nuclear bomb.
The BBC's Frances Harrison in Tehran says Iran maintains it has the right to peaceful nuclear power.
It says it will never accept a permanent cessation of enrichment.
Two previous summits in Vienna, Austria, failed to reach agreement.
Diplomats say there is a deadline of mid-November for a conclusion to these talks and if they fail, Europe will back American calls to refer Iran to the UN Security Council.
But Iranian officials have dismissed that as an empty threat.
Our correspondent says with oil prices already so high, they believe the West cannot afford to embargo Iranian oil, and they are hoping China will veto any vote against them in the Security Council.