Jordan, home to tens of thousands of Syrians who have fled the conflict in their neighboring country, plans to set up a third camp near the border for unmarried male refugees, an official said on Wednesday.

"The government has allocated 100 dunums (10 hectares/24.7 acres) to receive 18,000 single refugees. Saudi Arabia will provide 1,800 tents," Anmar Hmud, a government spokesman for Syrian refugee affairs, told state-run Petra news agency.

Syria's feared security forces arrested a Syrian Arab Red Crescent official and ambulance team leader in Damascus, a leading opposition bloc said on Wednesday, without specifying the reason.

Mohammed Raed al-Taweel, 36, was arrested last Thursday at a Red Crescent branch in the Abu Rummaneh district of Damascus, said the Syrian National Council.

The United States is closely watching developments in Gaza following the killing Wednesday of Hamas' military chief in an Israeli air strike, a Pentagon spokesman said.

"We're monitoring the situation closely. We stand by our Israeli partners in their right to defend themselves against terrorism," Lieutenant Colonel Stephen Warren said.

Russian Foreign Minister Sergei Lavrov arrived in Riyadh for talks with his Arab counterparts in the Gulf on Wednesday that are expected to highlight differences on the conflict in Syria.

Lavrov began his visit by meeting with Saudi Foreign Minister Saud al-Faisal, an AFP correspondent reported.

Israel killed a top Hamas military chief in an air strike in Gaza on Wednesday and launched a military operation against the Palestinian enclave, prompting Hamas’ armed wing to warn that the Jewish state had opened "the gates of hell."

Egypt said it was recalling its ambassador over Israel's hit on a car in Gaza City that killed Ahmed Jaabari and his bodyguard, followed by more than 20 air strikes in Gaza that killed another six people and wounded 65, according to the Hamas health ministry and rescue services.

Four explosions which hit a small Israeli community along the Egyptian border on Wednesday are believed to have been caused by rockets fired from Sinai, an Israeli security source told Agence France Presse.

The incident took place in Bnei Netzarim which lies 1.5 kilometers (just under a mile) from the Egyptian border, and some five kilometers (three miles) from the southernmost tip of the Gaza Strip.

A Turkish court sentenced a Syrian national on Wednesday to over 12 years in prison for allegedly spying in refugee camps near the border with the conflict-wracked nation, the Anatolia news agency reported.

The court had initially sentenced Sbahi Hamdo and his Turkish accomplice to 15 years in prison for "gathering confidential state information with the aim of political or military espionage".

A meeting of the Syrian opposition hosted by the Qatari capital amounted to a "declaration of war," the country's deputy foreign minister, Faisal Muqdad, said on Wednesday, describing France's decision to recognize the opposition alliance as "immoral.”

"The Doha meeting was a declaration of war. These people (the opposition) don't want to solve the issue peacefully through the mechanisms of the U.N.," Muqdad told Agence France Presse.

Israel's foreign ministry has proposed in a policy paper "toppling" Palestinian president Mahmoud Abbas if a Palestinian bid for state observer status at the United Nations is approved later this month.

"Toppling Abu Mazen's (Abbas's) regime would be the only option in this case," the position paper obtained by Agence France Presse says. "Any other option... would mean waving a white flag and admitting the failure of the Israeli leadership to deal with the challenge."

A meeting in Tokyo later this month aimed at increasing pressure on the Syrian regime could include several Southeast Asian countries, Japanese officials said Wednesday.

The November 30 meeting will bring together senior government officials from the "Friends of Syria Group" supporting the Syrian opposition and will focus on making sanctions more effective, a foreign ministry official said.