The negotiations between Iran and six world powers on the former's nuclear program were held in a " good and constructive" atmosphere in New York on Friday, the senior Iranian negotiator, Abbas Araqchi, was quoted as saying by Tasnim news agency on Saturday.

"There exist differences on the issues, but the atmosphere is good and constructive and the whole parties also have the determination and seriousness" to tackle the issue, said Araqchi, who is also Iran's Deputy Foreign Minister.

Iranian negotiators have held separate bilateral meetings with delegates from the United States, Russia, France and Britain on Thursday and Friday, he said, adding that the bilateral talks will go on the next days.

Talks on Saturday will focus on the technical discussions concerning Iran's nuclear program, he added.

Asked whether a high-ranking meeting would be possible on the issue, Araqchi said a ministerial meeting is likely at the weekend provided that "good progress" is achieved in the ongoing experts- level talks.

Fresh round of talks between Iran and the P5+1 group (including Britain, China, France, Russia, the United States and Germany) started on Friday in New York. The talks are expected to last until Sept. 26.

In July, Iran and the six countries agreed to extend negotiations over Iran's controversial nuclear program for another four months till Nov. 24 as they could not narrow down the significant gaps on core issues during the past six months.

An interim deal, which took effect on Jan. 20, was designed to buy time for negotiations. Under the deal, Iran would suspend some sensitive nuclear activities in exchange for a limited sanction relief.