U.S. Secretary of State John Kerry said Tuesday he would visit Russia next week for the first time since taking office, with a host of issues including the war in Syria clouding bilateral ties.

His announcement came the day after President Barack Obama stepped up pressure on Moscow over Syria, telling Russian leader Vladimir Putin of his concern about the reported use of chemical weapons by the Damascus regime.

Jordan on Tuesday warned the U.N. Security Council that the growing exodus of Syrian refugees was a threat to its stability and the council is now considering a visit to the camps.

Jordan faces a "crushing weight" if the refugee numbers, already over 500,000, keep growing at the current rate, said the ambassador, Prince Zeid al-Hussein, after a private meeting with Security Council envoys.

U.S. Ambassador to Lebanon Maura Connelly on Tuesday met with Greek Orthodox Patriarch of Antioch and All the East Youhanna X, reiterating her country's call for the “immediate release” of two Orthodox bishops who were kidnapped in the Syrian province of Aleppo.

“Connelly condemned in the strongest terms the kidnapping of the Patriarch’s brother, Archbishop Metropolitan Paul of Aleppo, and Syriac Orthodox Archbishop Mor Gregorios Yohanna Ibrahim of Aleppo, and repeated the United States’ call for their immediate release,” said a statement issued by the U.S. embassy.

President Barack Obama Tuesday warned against a rush to judgment on Syria's use of chemical arms, but said proof of their use would trigger a "rethink" of his reluctance to use military force.

As critics complain that he let Syria cross a U.S. "red line," Obama said Washington believed chemical weapons had been used in the country's vicious civil war but did not know exactly who had fired them.

The Mustaqbal bloc accused on Tuesday the March 8 camp of placing “impossible” conditions over the formation of a new government.

It warned in a statement after its weekly meeting: “The demands are part of its ongoing efforts to take over Lebanon.”

Syrian deputy Foreign Minister Faisal al-Meqdad on Tuesday stopped at Beirut's Rafik Hariri International Airport before heading to Syria by land, the state-run National News Agency reported.

“Al-Meqdad was coming from a three-days trip to Asia,” the NNA elaborated.

Russia's air transport agency on Tuesday banned all Russian civilian planes from flying through Syrian air space after the crew of a Russian passenger jet reported coming under threat over the war-torn country.

The federal agency Rosaviation said the ban on flights over Syria went into force on Monday and will remain until further notice.

President Michel Suleiman condemned on Tuesday the failed assassination attempt against Syrian Prime Minister Wael al-Halqi and the car bombing in front of the Syrian Interior Ministry in Damascus' Marjeh district on Tuesday.

He said: “Dialogue among all parties is necessary to reach a political solution that will lead to national reconciliation in Syria.”

A rebel victory in Syria's civil war would be the most positive outcome for Israel despite fears of instability and a stronger jihadist presence on the Golan should the regime collapse, analysts say.

The Syrian conflict has increasingly affected the Jewish state, as alarm mounts over the deployment of President Bashar Assad's chemical weapons arsenal and the potential for it to fall into the hands of non-state militant groups.

A blast in the central Damascus district of Marjeh on Tuesday killed at least 13 people, Syrian state television reported, a day after Prime Minister Wael al-Halqi survived a bomb attack elsewhere in the capital.

"The number of casualties in the cowardly terrorist blast targeting the commercial and historic center of Damascus in the Marjeh district rose to 13 martyrs and more than 70 injured," state television reported, citing the interior ministry.