Top diplomats from Russia, the U.S., Saudi Arabia and Turkey on Friday failed to make any major breakthrough on how to end the Syrian conflict, with the sides sharply at odds on the future of Bashar Assad.

But Moscow did seem to make progress with getting some more regional players on side, announcing with Jordan that the two countries would begin to "coordinate" their air operations over Syria. 

Turkey was in shock on Thursday after a man threw acid at toddlers at a popular restaurant in Istanbul, injuring seven, media reports said.

A three-year-old was left scarred and partially blind while another six children suffered burns after the man sprayed them with acid in the playroom of the Develi restaurant in the city's upscale Atasehir district, the Hurriyet daily said.

A 15-year-old schoolboy has been detained by police in Turkey for allegedly "insulting" President Recep Tayyip Erdogan, local media reports said Thursday.

The teenager, identified by the initials U. E., spent Wednesday night in a police station after being stopped by officers outside an Internet cafe, Cihan news agency said.

Curfews, street barricades and armed police everywhere: the unrest in Turkey's mainly-Kurdish southeast is likely to have an impact on the upcoming election but it also risks spelling a defeat for democracy.

Nestled near the border with Syria and Iraq, the city of Cizre became a symbol of the bloody conflict after violent clashes between Turkish security forces and the youth wing of the Kurdistan Workers Party (PKK) last month.

Any political transition period in war-torn Syria must be part of a "formula" which guarantees the departure as soon as possible of President Bashar Assad, Turkish Prime Minister Ahmet Davutoglu said Wednesday.

"The focus should not be on a transition period with Assad, but on a formula that will see him go and such formula should be implemented as soon as possible," he said at a press conference.

German Chancellor Angela Merkel and Turkish Prime Minister Ahmet Davutoglu on Sunday hailed a better understanding between Ankara and the European Union in dealing with the refugee crisis, as thousands more migrants poured into Slovenia headed for western Europe.

Merkel held talks in Istanbul with Davutoglu and was meeting President Recep Tayyip Erdogan on a critical one-day visit which came as Germany was shaken by a bloody knife attack on a pro-refugee politician.

Croatia on Saturday diverted the flow of thousands of migrants toward Slovenia after Hungary sealed its border to block the path of the streams of refugees desperate to reach northern Europe.

Slovenia received the first buses from Croatia transporting the migrants as a much-hyped EU deal with Turkey to defuse the crisis -- which has seen some 600,000 mostly Syrian migrants enter the EU this year -- began to look shaky.

The U.S. military on Friday denied claims that Syrian Kurdish forces had snagged ammunition from a massive air drop that was intended for Syrian Arabs fighting Islamic State jihadists.

The issue is sensitive for the Pentagon, which fears souring relations with Ankara and jeopardizing the use of a base at Incirlik in southern Turkey to conduct air raids against IS.

Turkish fighter jets shot down an unidentified drone which entered its air space near the Syrian border, with the U.S. military saying "all indications" showed that the unmanned vehicle was Russian.

If confirmed, the presence of a Russian craft in the air space of the key NATO member would further ratchet up tensions over Moscow's behavior in Syria. Russia denied it was to blame, despite repeated previous violations.

Turkey is confronting the uncomfortable prospect the suicide bombers behind the Ankara attack were homegrown jihadists who were radicalized at home and already known to the authorities as a potential menace to society.

Ninety-nine people were killed on October 10 when two suicide bombers detonated their charges in a gathering of union, leftist and Kurdish activists in the heart of the Turkish capital.