"Anyway, we have made much progress on the final text, but the progress on its annexes has not been desirable and work(ing on these annexations) continues," Araqchi told the state TV upon arrival at the Vienna airport on Thursday.

He underlined that Tehran and the world powers should still pave a difficult way in drafting the final deal.

Meantime, Araqchi expressed the hope that the two sides would be able to finish drafting the comprehensive agreement before the deadline.

Asked about the hues and cries on inspection of Iran's non-nuclear sites, he said, "I have explained this many times that there is no difference between inspection and visiting the military and non-military centers, that are, in fact, non-nuclear; we don’t accept such a thing."

"What has been raised within the framework of the Additional Protocol pertains to managed access to these centers," Araqchi underlined.

In relevant remarks on Sunday, Iranian Foreign Minister Mohammad Javad Zarif who held a meeting with his US counterpart John Kerry in Geneva on Saturday said that differences over the contents of a final nuclear deal are still in place.

"There are still numerous differences, and efforts will be made in various meetings so that these differences will be reduced to minimum levels and they will be studied in the next ministerial meeting," Zarif told the state-run TV.

He said the "differences are mainly those that have been discussed publicly".

Zarif also pointed to the West's demands to inspect Iran's military sites, and said the country's views have earlier been raised by the Iranian officials, including Supreme Leader of the Islamic Revolution Ayatollah Seyed Ali Khamenei, and a decision has been made to study other solutions to resolve this problem.

Talks are underway among the delegations of the seven nations to draft the final deal.