The apparent disintegration of a key Syrian rebel group has dealt a major blow to U.S. efforts to build up a force of moderate fighters to take on the Islamic State group.

The Hazm movement was seen as a cornerstone of the train-and-equip program Washington hopes will bring thousands of non-extremist fighters to bear against IS in Syria.

A Turkish Airlines plane carrying 224 passengers had to be evacuated after it skidded off the runway on landing at Kathmandu airport on Wednesday and ended up on grassland.

Nepal aviation officials said no one on board was injured, although one witness described how terrified passengers leaped from their seats as the cabin filled with smoke after the plane skidded to a halt.

Syrian President Bashar Assad accused his Turkish counterpart Recep Tayyip Erdogan of backing extremism as he met Tuesday with visiting Turkish opposition figures.

"Erdogan leads with a destructive policy that does not serve at all the interest of his people, by supporting takfiri (extremist Sunni) forces," state news agency SANA quoted Assad as saying. 

Every meal that goes before Turkish President Recep Tayyip Erdogan is rigorously tested both at home and abroad for fear of possible assassination, his personal doctor said.

And now a special food analysis laboratory will be built at Erdogan's controversial presidential palace to make sure all his food is safe to eat, Cevdet Erdol told the Hurriyet newspaper on Tuesday.

The Turkish military has launched disciplinary proceedings against a soldier for failing to resist Islamic State (IS) insurgents after he went missing on the border with Syria, media reported on Monday.

Ozgur Ors, a non-commissioned officer, went missing in January after he crossed the border into Syria from the southeastern Turkish province of Kilis in an operation to capture a group of smugglers.

Turkish President Recep Tayyip Erdogan arrived Monday in Riyadh for a visit at the king's invitation in what is seen as a Saudi bid to unify Sunnis against Iran and jihadists.

Erdogan's meeting with King Salman comes a day after Egyptian President Abdel Fattah al-Sisi held talks with the monarch, and precedes a visit by Pakistan's Prime Minister Nawaz Sharif later this week.

Kurdish rebels on Sunday hailed as "historic" a call for disarmament made by their jailed leader for disarmament and said Turkey should speed up reforms to move the peace process forward.

Abdullah Ocalan, the head of the Kurdistan Workers' Party (PKK) imprisoned on an island near Istanbul, had on Saturday urged the separatists to hold a congress on disarmament in the coming months.

Security footage appears to show three British girls, believed to be heading for Syria to join Islamic State (IS) militants, waiting at a bus station in Istanbul before traveling to a Turkish town on the Syrian border, media reported Sunday. 

Close friends Kadiza Sultana, 16, and 15-year-olds Shamima Begum and Amira Abase, boarded a flight from London to Istanbul on February 17. 

The jailed leader of the Kurdish Workers' Party (PKK) on Saturday made a "historic" call to the separatists to hold a disarmament conference, a key step in efforts to end Turkey's 30-year Kurdish insurgency.

"As we are ushering the 30 years of conflict towards permanent peace, it is our primary goal to reach a democratic solution," Abdullah Ocalan said in a message relayed by Peoples' Democratic Party (HDP) lawmaker Sirri Sureyya Onder. 

International monitors said the conflict in Ukraine was at a "crossroads" as further losses among government forces rattled a two-week-old truce just as it seemed to be gaining traction.

The deaths of three Ukrainian soldiers after a two-day lull in clashes with pro-Russian separatists highlighted the fragility of the ceasefire as the U.N. said some five million people needed humanitarian aid due to the conflict.