In a game of high-stakes diplomatic brinkmanship, global powers were readying Wednesday for a late-night push to reach a deal curbing Tehran's nuclear ambitions and ending a 13-year standoff.

With all bets off after ministers missed yet another deadline to seal the accord, U.S. Secretary of State John Kerry was huddling with his team in a rainy Vienna to pore over documents seeking to find a way forward.

Syria's parliament on Tuesday approved a deal with Iran under which Tehran will provide the government a new line of credit worth $1 billion, state media said.

The credit line will be the third that Tehran has extended to Damascus since the conflict in Syria erupted with anti-government protests in March 2011.

Global powers wrestling for a historic nuclear deal with Iran gave themselves yet more time Tuesday after foreign ministers failed to bridge what one diplomat called "very, very, very tough" remaining issues.

Iran and the P5+1 group -- the United States, Russia, China, France, Britain and Germany -- effectively gave themselves until Friday to agree a deal by extending the terms of a 2013 interim accord under which Iran has been curtailing its nuclear program in return for sanctions relief.

The U.N.'s atomic watchdog and Iran held "intense discussions" in Tehran on Monday about the possible military dimensions of the country's nuclear program, an Iranian official said.

The meeting was held as parallel talks were underway in Vienna between Iran and world powers on the eve of a deadline for what would be a historic accord on the country's suspect nuclear drive.

Marathon Iran nuclear talks appeared to be stumbling Monday as foreign ministers grappled to resolve the last hurdles blocking a deal, amid warnings that years of negotiations may fail at the 11th hour.

Foreign ministers from the global powers leading the talks to rein in Iran's suspect nuclear program huddled for the first time with the Iranian delegation during this 10-day stretch of talks in Vienna.

Jordanian authorities have foiled a "terrorist" attack and arrested an Iraqi man in possession of explosives said to have come from Iran's Revolutionary Guards, a judicial source said on Monday.

"Security services thwarted a terrorist plan at the last minute which was going to be carried out by an Iraqi on behalf of Iran's Quds Force," the source told AFP, without providing further details.

Global powers upped the pressure on Iran late Sunday warning now was "the time" to strike an elusive deal curbing its nuclear ambitions, as the U.S. said the fate of the talks hung in the balance.

U.S. Secretary of State John Kerry stressed that after almost two years of negotiations and on the ninth day of these latest talks "genuine progress" had been made.

A long-delayed investigation into whether Iran has sought to develop nuclear weapons could be completed by the end of the year with Tehran's help, the head of the U.N. atomic watchdog said Saturday.

Following his talks in Tehran earlier this week, U.N. watchdog chief Yukiya Amano said "progress was made on the way forward, but more work is needed."

A nuclear deal with Iran has "never been closer", Iranian Foreign Minister Mohammad Javad Zarif said in a message Friday, also holding out the promise of greater cooperation to tackle wider global problems.

Speaking in English from the balcony of the Viennese hotel hosting the nuclear negotiations, Zarif said at "this 11th hour despite some differences that remain, we have never been closer to a lasting outcome."

World powers and Tehran are close to a deal on curbing Iran's nuclear ambitions and the marathon negotiations look set to be successfully concluded "in the coming days," Russia's top negotiator said Thursday.

"I can't predict how many hours it will take to resolve this situation. But all parties are of the opinion that this matter will be resolved in the coming days," negotiator Sergei Ryabkov told the Russian TASS news agency.