A senior French diplomat paid a brief visit to Tehran to discuss "solutions" to end the bloody crisis in Syria, Iranian foreign ministry spokesman Abbas Araqchi said.

The director of the North Africa and Middle East section of the French foreign ministry, Jean-Francois Girault, met on Monday with Iranian deputy foreign minister Hossein Amir Abdollahian, Araqchi said.

Iran on Tuesday said it regretted Bahrain's move to ban the kingdom's opposition groups from having contact with Hizbullah, a close ally of Tehran.

"Bahrain's stance towards Hizbullah is regretful," foreign ministry spokesman Abbas Araqchi said at his weekly press conference.

Hizbullah has hurled itself into the war in Syria at the behest of its mentor Iran at the risk of damaging its reputation in the Arab world, experts say.

The powerful Shiite movement has won widespread support outside Lebanon for standing up to Israel on the battlefield.

Iran's defense minister insisted on Saturday that the country has never sent "military forces" to Syria, reiterating its denial of allegations by Western powers backing Syrian rebels.

"The Islamic Republic of Iran has never sent military forces to Syria and will never do so," Ahmad Vahidi said in a statement reported by Iranian media.

International efforts to organize a Syria peace conference are at fever pitch, but in Jordan's Zaatari camp, Syrian refugees are more concerned with the misery of their daily lives than diplomatic maneuvering.

"To be honest, we're fed up with these conferences, there have been many... without results. We want a radical solution," said Saleh, a former laborer from Syria's southern Daraa province.

The U.S. Treasury on Thursday added 20 companies and individuals to its Iran sanctions blacklist, accusing them of supporting Tehran's nuclear efforts and helping the country avoid international sanctions.

The 20 include Iran-based transport and freight companies Aban Air, DFS Worldwide and Everex, as well as officials of the three, which the Treasury said work to get around bans on doing business with already-blacklisted Iran Air.

Tehran on Thursday denied a Bahraini claim it had found an Iranian drone in the sea near Saudi Arabia, and urged Manama to refrain from making "baseless accusations", the ISNA news agency reported.

It cited an unnamed foreign ministry source as denying Bahrain's assertion that the downed aircraft was Iranian.

Bahrain on Wednesday said it has found an Iranian drone in the kingdom's north near Saudi Arabia and called for increased cooperation between regional security services to face "threats" from Tehran.

The unmanned aircraft "was found in the sea in north Bahrain, mainly between Bahrain and Saudi Arabia, two weeks ago," government spokeswoman Samira Rajab told Agence France Presse.

Iran is making significant progress in expanding its nuclear program, including in opening up a potential second route to developing the bomb, a new U.N. atomic agency report showed Wednesday.

The International Atomic Energy Agency's latest quarterly update said that Tehran has accelerated the installation of advanced uranium enrichment equipment at its central Natanz plant.

France on Wednesday condemned Iran's disqualification of hundreds of would-be presidential candidates, saying the Iranian people should be allowed to "freely choose" their leaders.

Ahead of the June 14 election to replace Mahmoud Ahmadinejad, the conservative-dominated Guardian Council winnowed the candidate field from 686 to eight, all close to supreme leader Ayatollah Ali Khamenei.