Armed tribesmen kidnapped two expatriate employees of the International Committee of the Red Cross and their interpreter in southern Yemen on Monday, witnesses and militia sources said.

The Swiss and Kenyan ICRC staffers were abducted in the southern city of Jaar, which was held by loyalists of al-Qaida for 12 months until it was recaptured by the army in June last year, militia commander Hussein al-Wahayshi said.

Israeli Prime Minister Benjamin Netanyahu is to hold talks on Tuesday with Russian President Vladimir Putin on the conflict in Syria, the Kremlin said, amid concerns Moscow plans to deliver advanced missiles to the Damascus regime.

"During the meeting an exchange of opinion is planned on key aspects of bilateral ties," the Kremlin said in a statement.

Tribal gunmen kidnapped on Monday a Swiss man working for the International Committee of the Red Cross in southern Yemen, a local pro-government militia leader said.

The gunmen who belong to Al-Marakisha tribe kidnapped the man in the city of Jaar, in Abyan province, said Hussein al-Wahayshi, a local commander of the Popular Resistance Committees.

Syria's key National Coalition opposition group will meet May 23 to discuss a U.S.-Russian proposal for an international conference on a political solution to the Syrian conflict.

"The meeting will take place in Istanbul and last three days... to take a decision on the Kerry-Lavrov proposal and our participation," Coalition spokesman Sonir Ahmed told Agence France Presse, referring to U.S. Secretary of State John Kerry and his Russian counterpart Sergei Lavrov.

Vice Admiral John Miller, commander of the U.S. Fifth Fleet, said on Sunday that a massive naval minesweeping exercise involving 41 countries was not directed at Iran.

"It is not about Iran," Miller said at a news conference in the Bahraini capital Manama, the fleet's headquarters, saying the maneuvers were "purely defensive".

King Mohammed VI of Morocco has urged the conservative Istiqlal party to go back on a decision to pull out from the Islamist-led government, a spokesman for the party said on Sunday.

Istiqlal's national council, the main ally of the ruling Islamists, announced on Saturday it was pulling out of the government over its failure to shore up the economy and solve dire social issues.

Saudi Arabia's interior minister on Sunday discussed security cooperation with Yemen, home to Al-Qaida in the Arabian Peninsula (AQAP), Yemen's official Saba news agency reported from the neighboring kingdom.

Prince Mohammed bin Nayef discussed with Yemeni Foreign Minister Abu Bakr al-Qirbi in Saudi Arabia "strengthening bilateral security cooperation for preserving security in both countries," Saba said.

The European Commission announced on Sunday an additional 65 million euros ($84 million) in aid for Syrian refugees and internally displaced, warning the crisis is "already at breaking point".

The announcement came in a statement released to coincide with a visit to Syrian refugees in Jordan by humanitarian aid commissioner Kristalina Georgieva.

Former U.S. defense secretary Robert Gates warned Sunday that deepening U.S. military involvement in Syria's civil war would be a "mistake," warning the outcome would be unpredictable and messy.

In an interview with CBS's "Face the Nation," Gates also said he saw "no good outcomes" in dealing with Iran's nuclear program and warned that a full U.S. withdrawal from Afghanistan would be "a disastrous mistake."

Tunisian forces prevented on Sunday Salafists in two cities in the southeast from pitching tents to preach in, the private Shems FM radio reported, a day after police fired tear gas at the radical Islamists in the capital Tunis.

Police dispersed "without violence" Salafists trying to set up a tent in front of the headquarters of the governorate in Tataouine, 550 kilometers (around 365 miles) south of Tunis, the radio's correspondent said from the site.