Turkey said Sunday it had arrested nine people over bombings that killed 46 in a town near the Syrian border and warned Damascus a red line had been crossed.

The Syrian government denied involvement in the twin car bombs that sowed death in Reyhanli on Saturday but Ankara said it was holding suspects who had confessed and accused Damascus of dragging Turkey into its civil war.

The attacks were the deadliest case of what observers see as an increasing regionalisation of the conflict that started in March 2011 and came as key brokers Washington and Moscow made an unprecedented joint push for peace talks.

"They want to drag us down a vile path," Turkish Prime Minister Recep Tayyip Erdogan said at a rally in Istanbul, urging Turks to be "level-headed in the face of each provocation aimed at drawing Turkey into the Syrian quagmire."

Speaking during a visit to Berlin, Foreign Minister Ahmet Davutoglu called the attacks a breach of Turkey's "red line" and warned that Ankara reserved the right to "take any kind of measure" in response.

Cranes were seen lifting debris from buildings destroyed by Saturday's blasts in Reyhanli, a major Turkish hub for Syrian refugees and rebels.

The attacks provoked a backlash against Syrian refugees as rampaging crowds wrecked dozens of cars, according to witnesses.

The attack sowed panic in Reyhanli, a town of about 60,000 people.

"I heard the first blast, walked out, thinking it was a missile being fired from Syria. Then I found myself on the ground, my arms and right leg hurting, my ears ringing. It must have been the second bomb," said Hikmet Haydut, a 46-year-old coffee shop owner who had minor injuries to his head and body.

"I am alive, but all I have is gone."

Deputy Prime Minister Besir Atalay told a news conference that nine people -- all Turks -- were detained for questioning and that some had confessed involvement in the attacks, which also left dozens wounded.

Interior Minister Muammer Guler said the explosives were smuggled into the area, then placed into Turkish vehicles with special compartments to conceal their deadly cargo.

-- "A spark transforms into a fire" --

The suspects were said to belong to a Turkish Marxist organisation with direct links to Syrian President Bashar al-Assad's regime.

Damascus rejected the allegations that it masterminded the attacks.

"Syria did not commit and would never commit such an act because our values would not allow that," Information Minister Omran al-Zohbi said.

"It is Erdogan who should be asked about this act... He and his party bear direct responsibility," he added.

NATO member Turkey distanced itself from its erstwhile ally soon after Assad started cracking down on pro-democracy protests in 2011.

Ankara has since become a rear base for the Syrian rebellion, and Damascus has already been blamed for a string of attacks on Turkish soil.

Can Dundar, a columnist at Turkey's Milliyet newspaper, argued that it was late to warn against attempts to drag Ankara into the Syrian conflict.

"Turkey seems to be sinking into the Syrian swamp... It has become a stakeholder in this civil war by directly supporting the opposition," he wrote.

The Syrian opposition National Coalition said the attacks were designed to drive a wedge between Turks and Syrians and called for more robust international action against Assad's regime.

Neighbours have been increasingly involved in or affected by the ever escalating conflict, which has already left more than 80,000 people dead, hundreds of thousands homeless and large parts of Syria's main cities in ruins.

In recent days, Israel is reported to have bombed Syria twice, Lebanon's Hezbollah militia has admitted it was fighting alongside regime troops and Jordan has warned that Syrians could soon account for 40 percent of its population.

Davutoglu said it was "not a coincidence" the Reyhanli bombings occurred as international diplomatic efforts to solve the Syrian crisis were intensifying.

The United States and Russia, one of the few remaining supporters of Assad's regime, pledged this month to relaunch efforts to solve the conflict.

Davutoglu also said Ankara was looking at "connections" between the Reyhanli attack and an assault on a Sunni district of Banias, a Mediterranean city in Syria, this month where rights groups say at least 62 civilians were killed.

Erdogan is due to meet US President Barack Obama in Washington on Thursday.

The West swiftly denounced Sunday's attacks.

UN leader Ban Ki-moon said the perpetrators must be "brought to justice" and US Secretary of State John Kerry also condemned the "awful news".

But Ankara blamed the international community's silence for the failure to oust Assad.

"The latest attack shows how a spark transforms into a fire when the international community remains silent and the UN Security Council fails to act," Davutoglu said in Germany.

Erdogan has in recent weeks ramped up his rhetoric against Assad, calling him a butcher and accusing him of using chemical weapons in the conflict.

But German Defence Minister Thomas de Maiziere argued there were only "limited" options available to the international community.

"A military intervention would be very, very costly and would result in significant losses," he cautioned in an interview on German public television.