Russian Foreign Minister Sergei Lavrov and his U.S. counterpart John Kerry called on Wednesday for an agreement on a nuclear deal with Iran to be reached as soon as possible.

"The need to reach as soon as possible a comprehensive agreement which would allow to fully normalize the situation around the Iranian nuclear program has been acknowledged," the Russian foreign ministry said following a call between Lavrov and Kerry.

State television aired footage Wednesday of the test flight of a drone which Iran says it reverse engineered from a U.S. aircraft that came down over its territory in 2011.

The 30-second clip, broadcast before the midday news and filmed from a helicopter as well as from the ground, showed a delta-winged aircraft in flight.

Turkey could scrap a controversial plan to buy missile defense systems from China that alarmed the United States and its Western allies, Turkish and European sources said Wednesday.

Key NATO member Turkey said in September last year it was entering negotiations with the China Precision Machinery Export-Import Corporation (CPMIEC) to acquire its first long-range anti-missile systems.

A body tasked with policing the Internet laid down a two-month deadline Tuesday for Iran's government to regularize the use of Instagram or access to the site would be blocked.

Iranian authorities regularly block Twitter, Facebook and other social networking sites considered damaging to the values of the Islamic republic.

Russia's deputy foreign minister Sergei Ryabkov said Tuesday he was "reasonably optimistic" world powers can reach a nuclear deal with Iran by a November 24 deadline, despite big gaps remaining.

"We are not working on plan B, that's for sure," he told reporters in Muscat, though he did not rule out an extension. "If by whatever reason, by whatever development, we are not there, I think we will have time on the evening of the 23rd to develop an alternative."

The latest nuclear talks in Oman between Iran and Western powers ended on Monday without any progress, a senior Iranian negotiator said.

"We can no longer talk about progress in the negotiations, but we are optimistic that we can reach an accord" before the final November 24 deadline, Iran's deputy foreign minister Abbas Araghchi said, quoted by ISNA news agency, after two days of talks between Iranian, U.S. and EU officials.

Iran said Monday that a copy of an American drone downed over its territory in 2011 had successfully completed its first test flight, promising to release footage of the experiment.

Tehran captured the US RQ-170 Sentinel in December 2011 while it was in its airspace, apparently on a mission to spy on the country's nuclear sites, media in the United States reported.

Iran said on Monday that it was at Iraq's disposal to help its neighbor battle the Islamic State jihadist group, media reported.

Vice President Eshaq Jahangiri made the pledge during talks in Tehran with his Iraqi counterpart, former Premier Nuri al-Maliki.

U.S. President Barack Obama said a "big gap" remains in international nuclear negotiations with Iran and he questioned whether talks would succeed.

"Are we going to be able to close this final gap so that (Iran) can reenter the international community, sanctions can be slowly reduced and we have verifiable, lock tight assurances that they can't develop a nuclear weapon," Obama told CBS News in an interview broadcast Sunday.

Iran is still failing to provide answers in a probe into its nuclear activities, and is unlikely to do so before a November 24 deadline for a deal with world powers, the U.N. atomic watchdog said Friday.

"Iran has not provided any explanations" on two issues that Tehran had undertaken to clarify by August 25, the International Atomic Energy Agency said in a new quarterly report.