Moscow, June 25 (IANS/TASS): The text of a deal on Tehran's nuclear programme between Iran and the P5 1 group of world powers has been worked out almost 90 percent, a top Russian diplomat said on Thursday.

"I think it is around 90 percent," Russian Deputy Foreign Minister Sergey Ryabkov said ahead of flying to Vienna for a final round of talks.

"But this concerns the amount of the text, not the importance of the issues," the diplomat said.

He said a comprehensive agreement on Tehran's nuclear programme is likely to be reached by June 30 and is expected to guarantee a peaceful nature of the Iranian nuclear programme and make it possible to abandon the sanctions imposed on Iran.

US Secretary of State John Kerry and other top diplomats from P5 1 would travel to Vienna on Friday to take part in the nuclear negotiations, according to US State Department spokesman John Kirby.

Iranian Foreign Minister Mohammad Javad Zarif was scheduled to travel to Vienna on Saturday to join his deputies Abbas Araqchi and Majid Takht-e-Ravanchi, who have been holding talks about the text of a possible comprehensive deal on Tehran’s nuclear programme since June 17.

Iran and the P5 1 group are seeking to seal a comprehensive deal based on the mutual understanding on the key parameters agreed upon in the Swiss city of Lausanne on April 2.