President Barack Obama issued a stern defense of his outreach to Iran on Friday, warning U.S. lawmakers not to derail diplomatic efforts to curtail the Islamic state's nuclear program.

In an end-of-year news conference, Obama said efforts in Congress to pass tougher economic sanctions could damage recent moves to halt Tehran's alleged drive to refine nuclear fuel and build a weapon.

Washington is standing firm on its stance that Iran has no place at a long-awaited Syria peace conference in Switzerland next month, a senior U.S. administration official said Friday.

"We find it difficult to imagine them at this conference," the official told reporters on condition of anonymity.

French Foreign Minister Laurent Fabius cast doubt Thursday on the chances of a final nuclear deal between the West and Iran, as delicate talks were set to resume in Geneva.

Fabius, one of the key players in the negotiations with Tehran, told the Wall Street Journal that he was unsure if the Islamic republic would dismantle all its nuclear capabilities to a degree where making a weapon would no longer be possible.

The Senate's Democratic leadership is shielding U.S. President Barack Obama from potentially embarrassing fallout by refusing to vote on new sanctions against Iran, the chamber's top Republican warned Wednesday.

Lawmakers from both parties are keen to expand economic penalties on Iran, which is in the midst of negotiations with world powers over its nuclear program.

Talks between experts from Iran and world powers on implementing last month's nuclear deal will resume on Thursday in Geneva, a spokeswoman for EU foreign policy chief Catherine Ashton said Wednesday.

"The technical talks will be resumed tomorrow and continue until Friday" in Geneva, Nabila Massrali told Agence France Presse via email.

The West's policies on Iran and Syria are a "dangerous gamble" and Saudi Arabia is prepared to act on its own to safeguard security in the region, a top Saudi diplomat said Tuesday.

"We believe that many of the West's policies on both Iran and Syria risk the stability and security of the Middle East," the Saudi ambassador to Britain, Prince Mohammed bin Nawaf bin Abdulaziz, wrote in a commentary in the New York Times.

Foreign Minister Mohammad Javad Zarif has expressed Iran's "discontent" to his U.S .counterpart over the expansion of a blacklist of Iranian firms following a landmark nuclear accord, media reported Monday.

Iran has accused Washington of going against the spirit of the deal reached in November by adding a dozen overseas companies and individuals to its blacklist for evading sanctions imposed on Tehran over its controversial nuclear program.

Iranian security forces have arrested a "spy" working for the British government in Kerman, a judicial official in the southeastern province told the state IRNA news agency on Saturday.

The announcement came just a day after Iran's new envoy to Britain, Hassan Habibollah-Zadeh, held talks in London on his first visit since his appointment last month, which ended a two-year freeze in diplomatic relations.

Iran's president said Saturday that the Islamic Republic has successfully sent a monkey into space for the second time, part of a program aimed at manned space flight.

Hassan Rouhani's website president.ir said that the launch of the rocket dubbed Pajohesh, or Research in Farsi, was Iran's first use of liquid fuel. It said the monkey, named Fargam or Auspicious, was returned to earth safely.

The White House insisted Friday that a U.S. man reportedly working for the CIA when he went missing in Iran six years ago was not a U.S. government employee.

Reports by The Washington Post and the Associated Press on the fate of Robert Levinson said the U.S. spy agency had been paying the former FBI agent to gather intelligence.