Iranian nuclear talks has "real gaps" on key issues": Kerry

Stakeholders will continue working to bridge the remaining "real gaps" in Iranian nuclear talks while tangible progress has been made, U.S. Secretary of State John Kerry told reporters here on Tuesday.

"There has been tangible progress on key issues, ... however, there are also very real gaps on other key issues," Kerry noted, but he declined to talk the details.

The remarks came after days of intensive and lengthy bilateral and trilateral meetings between top diplomats from the United States, Iran and other world major countries, as the July 20 deadline for a comprehensive agreement approaches.

Kerry and his Iranian counterpart Mohammad Javad Zarif from Sunday engaged in "very tough" negotiations which were sealed off to reporters.

"The Iranians are strong in their position and Zarif is a tough negotiator," Kerry said.

With the results of the direct U.S.-Iran talks, Kerry is returning to Washington on Tuesday to consult with President Barack Obama and Congress about the state of negotiations.

The West suspects Iran is seeking nuclear weapons. But Iran insists that its nuclear program is for peaceful purposes and denies the accusations.

There have been multiple rounds of negotiations in recent months between Iran and the so-called P5+1, the five UN Security Council permanent members, including the United States, Britain, France, China, Russia, plus Germany, seeking a deal to settle the decade-old disputes over Iran's nuclear issues.

A six-month interim deal, which took effect on Jan. 20 and would expire five days later, was designed to buy time for negotiations on a final agreement.

Under the interim deal, Iran agreed to suspend some sensitive nuclear activities in exchange of limited sanction relief.

Kerry said "the July 20 deadline is still on the table", but he indicated that the possibility to extend the talks beyond the July 20 deadline would also be discussed.

"It is clear we have more work to do," Kerry said, adding that he believes "there is a path forward".

Kerry warned earlier this month that if there is no enough progress in the talks by July 20, the United States may not allow them to continue.

It is known that, Iran and the six major countries remain far apart on the permissible scope of the Islamic Republic's uranium enrichment, which is an enormous roadblock to the final agreement.

Iran now operates about 10,000 centrifuges to enrich uranium.

Last week, Iran's supreme leader Ayatollah Ali Khamenei said that Iran wanted to expand its enrichment capacity to 19 times the amount it is now using. Meanwhile, the Obama administration wants to reduce the amount to a "fraction" of its current size.

"190,000 centrifuges are too many," Kerry said, urging Iran to convince the world with "concrete" actions of its peaceful nuclear ambitions.

Time is running short and gaps remain wild. "The critical point is, when there is a path forward, Iran needs to chose take it," Kerry said.

The foreign ministers and deputy ministers from P5+1 group Sunday flew to Vienna to review the progress of the talks.

As no major progress reached during the meeting, the foreign ministers of Britain, France, and Germany left Vienna on the same day after pressing Iran to make concessions over core issues.

Experts believe that the negotiations could probably need more time to reach a final deal.