VIENNA, July 16 /ITAR-TASS/. Iran and the P5+1 (five permanent members of the U.N. Security Council and Germany) group may resume negotiations on a comprehensive agreement in September, a Western diplomatic source close to the negotiations said on Wednesday, July 16.

July 20, the current deadline for arriving at a comprehensive agreement, is only several days away but there are too many questions remain to be solved. The diplomat said, adding that the sides were considering extending the negotiations and holding a new meeting in September.

A diplomatic source in the Iranian delegation told ITAR-TASS earlier in the day that the deadline could be extended for weeks or even months.

Another source in the Iranian delegation told ITAR-TASS that the talks might be extended but to no longer than November 25, a year since the adoption of the Geneva document. The consultations may be extended until that date by mutual agreement of the sides.

Two weeks after the start of the current round, which was supposed to be the final one, Iran and the six world powers have not yet come to agreement on key aspects of Tehran’s nuclear programme.

What seemed highly unlikely at the beginning of the month can be more and more often heard from diplomats and chief negotiators: the sides may fail to agree the final document by July 20.

Even the heads of the delegations and ministers participating in the talks have stopped making forecasts. After three days of intensive consultations in Vienna, U.S. Secretary of State John Kerry said before flying home on Tuesday, July 15, that the chance to reach an agreement remained but all the same he would discuss a possible extension of the talks with U.S. President Barack Obama and Congress.

Iranian Foreign Minister Zavad Zarif was even less optimistic and said getting the agreement by July 20 was just a possibility and noted that Tehran had not decided yet whether it should continue the talks after July 20.

As diplomatic sources said before the start of the talks, much in their final rounds would be decided in consultations between Iran and the United States. But the tone of Kerry’s and Zarifi’s statements indicates a lack of progress up to date.

A source in the Iranian delegation sad Tehran’s enrichment programme was the main stumbling block at the talks. It was made clear to the Iranian delegation in Vienna that 19,000 centrifuges would be too much for an enrichment programme.

However, Zarif said on Tuesday, July 15, that Tehran would not give up its goal of having a serious but transparent enrichment programme to meet the needs of the country. He stressed that the Iranian nuclear programme was peaceful and Tehran had nothing to hide.

Another source in the delegation told ITAR-TASS that the lifting of a part of sanctions as an interim step would not satisfy Iran. He stressed that if the six world powers wanted to achieve substantial progress at the talks, the sanctions must be lifted in full.

A source close to the talks said that the negotiations between Iran and the United States were proceeding intensively but there were no significant changes in their positions yet.

Iranian President Hassan Rohani also said that the remaining “disputes can be resolved with goodwill and flexibility” to reach a permanent agreement before a July 20 deadline.

The interim nuclear deal made on November 24, 2013, called for taking the first step of reciprocal actions to prove good faith in a six-month period to be followed by negotiations for a comprehensive agreement, according to which the Western governments will acknowledge the Iranian nuclear programme as civilian.

The deal was called the first step to be followed by a comprehensive agreement, which, on the one hand, should resolve the international community’s concerns about the Iranian nuclear programme and, on the other hand, remove economic sanctions that slow down Iran’s economic development.

The agreement reached by and between Iran and the P5+1 (five permanent members of the U.N. Security Council and Germany) in Geneva last year became effective on January 20, 2014.