Turkish and U.S. officials Thursday began their first "operational planning" meeting aimed at bringing about the end of Syrian President Bashar Assad's embattled regime.

The meeting is expected to coordinate military, intelligence and political responses to the crisis in Syria where a deadly crackdown on peaceful protests that began in March 2011 has according to activists claimed more than 23,000 lives.

Clashes broke out overnight between Kurdish rebels and Turkish soldiers in the volatile southeastern Turkey, leaving 21 people dead, local security sources told Agence France Presse on Thursday.

Sixteen members of the outlawed Kurdistan Workers' Party (PKK) were killed in the fighting that erupted after the rebels ambushed a military convoy, killing five Turkish soldiers, said the sources.

At least nine people, including four children, have died from a car bomb in a southeastern Turkish city of Gaziantap, Turkey's deputy prime minister said Tuesday, raising the earlier toll.

"The toll from this terrorist attack is now nine dead, including four children," said Besir Atalay.

The Turkish national, Abdul-Basset Arslan, who was kidnapped in Beirut on Friday, is held by the families of the 11 Lebanese pilgrims who were seized in Syria in May.

“We obtained information that the families of the 11 abducted men kidnapped Arslan,” an official source told the pan-Arab daily al-Hayat on Tuesday.

A ministerial committee tasked with following up the case of the kidnapped Lebanese in Syria held a meeting on Tuesday without issuing a statement.

Labor Minister Salim Jreissati said after the talks that the next session will be held at Interior Minister Marwan Charbel’s office on Friday.

A car bomb exploded Monday, killing eight people and wounding 50 others in a city in south-east Turkey, the mayor of Gaziantap, Asim Guezelbey, told local television.

The powerful blast went off close to a police station, setting fire to several vehicles including a city bus, the mayor told NTV news channel which broadcast images of firefighters racing to put out the flames.

Turkey cannot handle more than 100,000 Syrian refugees and instead proposes a U.N. buffer zone inside Syria to shelter them, Turkish Foreign Minister Ahmet Davutoglu said in remarks published Monday.

"If the number of refugees increases to 100,000, we will not be able to shelter them in Turkey. We have to welcome them in Syrian territory" under U.N. auspices, Davutoglu told the newspaper Hurriyet.

Turkish authorities crossed the Syrian border Sunday to distribute humanitarian aid to Syrians who have been forced from their homes and are massed at the border, emergency officials said.

The authorities gave out food and other supplies on Syrian soil, just across the border from the southern Turkish town of Reyhanli, in a region where hundreds of displaced Syrians are waiting to enter Turkey, officials told Turkish news agency Anatolia.

Sources close to Interior Minister Marwan Charbel said the minister returned from Ankara with “great optimism” that he would reveal soon on the fate of 11 Lebanese pilgrims kidnapped in Syria since May.

The sources told An Nahar daily published Sunday that a visit by Charbel and General Security chief Maj. Gen. Abbas Ibrahim to Turkey was “fruitful.”

Turkish Foreign Minister Ahmet Davutoglu called on Speaker Nabih Berri on Saturday to take the necessary initiatives to guarantee the safe release of the two abducted Turkish nationals in Lebanon.

“He demanded Berri to press the release of the two Turkish nationals,” diplomatic sources told Anatolia news agency.