US Secretary of State John Kerry joined the Iranian nuclear talks with Iranian Foreign Minister Mohammad Javad Zarif and French Foreign Minister Laurent Fabius here on Saturday as the June 30 deadline approached.
The talks were the latest efforts in a bid to reach a long-term deal to end Tehran's disputed nuclear programme, Xinhua reported.
The sides made some progress on April 2 in Switzerland but significant gaps remain over the sequencing of sanctions relief and the clarification of Iran's controversial nuclear activities.
"If the other side ... takes positive steps and does not make excessive demands, we will certainly reach a deal that benefits everyone," Zarif was quoted as saying by state news agency IRNA.
Experts believe Tehran and the western states are quite close to a deal though some tough issue need to be settled.
French Foreign Minister Fabius said that at least three conditions are indispensable for the deal.
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"These are a lasting limitation of Iran's nuclear capacities in research and production. The second is a solid verification of sites including military bases if necessary. The third is an automatic return of sanctions in case of violations of the engagements made," he told reporters.
But he said this was not accepted by all the parties involved as yet.
Foreign ministers from all the sides involved are expected in Vienna in the coming days.
Western states have long suspected Iran of developing nuclear weapons under cover of its civilian atomic plan. However, Tehran has always denied the allegation saying its nuclear plan is peaceful.