The number of Syrians seeking asylum in developed nations tripled last year, the U.N. refugee agency said Thursday, amid an eight-percent overall rise in people looking for a safe haven in rich countries.

Syrian asylum claims in 44 industrialized countries jumped to 24,800 from 8,400 in 2011, the year the civil war began.

Russia backtracked Wednesday over claims that Syrian rebels had used chemical weapons, saying the information still had to be checked.

The foreign ministry said on Tuesday it had information from Damascus the rebels had used chemical weapons in an attack that day in Aleppo province that Syria claimed killed 16 people.

U.S. President Barack Obama on Wednesday warned the Damascus regime it would be held accountable for any use of chemical weapons against civilians in Syria in a move which would spark an international response.

Speaking at a joint news conference with Israeli Prime Minister Benjamin Netanyahu in Jerusalem, Obama said the use of chemical agents against the Syrian people would be a "grave and tragic mistake" and a "game-changer."

Palestinian militants pitched a protest camp Wednesday on the site of a contested Jewish settlement, in an act of defiance as U.S. President Barack Obama began an historic visit.

Israel's plan to build in a strip of West Bank land outside Jerusalem called E1 has sparked a major international backlash, with experts saying it could wipe out hopes for the establishment of a viable Palestinian state.

Germany said Wednesday it was prepared to take in another 5,000 Syrian refugees in the coming months in response to deteriorating conditions in the war-ravaged country.

Interior Minister Hans-Peter Friedrich said Berlin would grant asylum to 3,000 Syrians from June at the latest, followed by another 2,000 later this year in response to an "increasingly difficult" situation.

Syria's regime and rebels on Wednesday called for international investigations into an attack a day earlier in which each side accuses the other of having used chemical weapons.

State news agency SANA quoted the foreign ministry as saying "the government of the Syrian Arab Republic has requested that the secretary general of the United Nations form a specialist technical mission that is independent and impartial to investigate the terrorist use of chemical weapons in Khan al-Assal."

At least 12 key members of Syria's National Coalition said Wednesday they had suspended their membership in the main opposition body amid a row over the deeply divisive election of the first rebel prime minister.

The group of 12 included the Coalition's deputy Soheir Atassi and spokesman Walid al-Bunni.

Kuwait's appeals court on Wednesday toughened the jail term of an opposition tweeter to five years for calling for a coup and insulting the emir of the Gulf state.

Bader al-Rasheedi was jailed on November 28 after the lower court gave him a two-year term, but the appeals court decided to increase this to five years, director of the Kuwait Society for Human Rights Mohammad al-Humaidi told Agence France Presse.

Syria's embattled President Bashar Assad paid an unexpected visit to an educational center in the capital Damascus on Wednesday, the presidency said on its official Facebook page.

"President Assad made a surprise visit to the Educational Center for Fine Arts where the education ministry was honoring the families of students who were martyred as a result of terrorist acts, to honor the parents himself," the presidency wrote, alongside photos of Assad at the center.

U.S. Defense Secretary Chuck Hagel plans to visit the Jewish state in April to boost cooperation between the two countries, Israel's defense ministry said on Wednesday.

The plans were discussed during a telephone conversation between Hagel and new Israeli Defense Minister Moshe Yaalon, who took up the position on Monday, a ministry statement said.