Associated Press

By JOE PARKINSON and AYLA ALBAYRAK

Forensic officers work on Sunday, as army commandos patrol the scene of one of the car-bomb sites a day earlier in Reyhanli, Turkey.

REYHANLI, Turkey—Turkey on Sunday blamed groups connected to Syria’s intelligence service for two car bombings that killed at least 46 people in a Turkish border town a day earlier.

Turkish officials said Sunday that security services had arrested nine people, all Turkish citizens, including the alleged mastermind, after two car bombs ripped through Reyhanli, a small town close to Syria. Syria denied any involvement in the bombings.

Turkey’s interior minister, Muammer Guler, said an investigation showed that the huge blasts—which damaged almost 500 shops, 300 homes and 60 vehicles—were carried out by a “terrorist organization in close contact with Syria’s intelligence agency.”

Agence France-Presse/Getty ImagesAt a funeral on Sunday, mourners gather around the coffin of a victim who was killed in one of the two blasts.

The government didn’t immediately publish evidence that showed Syrian involvement, although Deputy Prime Minister Besir Atalay said a number of the suspects had confessed links to Syrian intelligence services.

Ankara said the blasts were an attempt by Damascus to sow discord and destabilize Turkey.

Saturday’s bombings marked one of the most deadly terror attacks ever in Turkey, a country whose conflict with Kurdish separatists has claimed 40,000 lives in the last two decades.

The incident came as Prime Minister Recep Tayyip Erdogan prepares to meet President Barack Obama in Washington on Thursday for talks on Syria amid renewed hope for a diplomatic push to end its war after Moscow and Washington announced a joint effort to bring the government and rebels to an international conference.

The bombings, which caused an outpouring of grief across Turkey on Sunday, also spotlight the challenge Ankara faces as it seeks to bolster international action to topple President Bashar al-Assad’s regime while avoiding a spillover that could destabilize the country’s own delicate ethnic mix.

Amid calls to respond to the attacks, Turkey’s leaders vowed to punish those responsible but also called for restraint. In comments that seemed to underline at the dangers of a unilateral military response and the potential for interethnic clashes inside Turkey, Mr. Erdogan warned against being sucked into Syria’s civil war.

“We have to be extremely calm against all kinds of provocations that are trying to pull us into the swamp in Syria,” Mr. Erdogan said in Istanbul.

In Damascus, Syria’s Information Minister Omran al-Zoubi rejected Turkey’s allegations, saying the bombs weren’t the behavior of the Syrian government and that “no one has the right to make false accusations.” Labeling Ankara a “terrorist Turkish government,” he blamed it for bringing foreign fighters, weapons and funds into Syria across the countries’ shared border.

Associated PressRelatives of a car-bombing victim mourned on Sunday in Reyhanli, Turkey, near the Syrian border.

Foreign Minister Ahmet Davutoglu said the news showed it was time for the international community to “define a joint stance” against Mr. Assad’s regime, without elaborating on what such a stance would entail.

Analysts said the pressure for Ankara to respond militarily if a connection to Damascus was proved was tempered by a lack of compelling military options and the domestic unpopularity of Turkey’s Syria policy.

Ankara has tried not to escalate tensions over the past year in response to events that have included the deaths of Turkish citizens in cross-border artillery fire, a car bomb in February that killed 14 people on the border and the shooting down of a Turkish jet by Syrian antiaircraft guns.

A pair of car bombs exploded in Reyhanli, a small Turkish town near the Syrian border. More than 40 people were killed and over 100 were injured by the blasts. Photo: Associated Press.

There was little sign on Sunday that Ankara was considering a military retaliation comparable to Israel’s strikes on Syria in recent weeks.

“There is now an expectation that the government will be able to show that it is ready to retaliate, but that is obviously a very difficult path given that there is very little that the government can do that it is not doing already,” said Sinan Ulgen, a former Turkish diplomat now at the Carnegie Endowment for International Peace.

Turkey, which shares a 565-mile border with Syria, has been a crucial supporter of the Syrian rebel cause and Ankara has allowed its territory to be used as a logistics base and staging center for Syrian insurgents.

The U.S. and other Western powers are reluctant to intervene directly and Turkey has sought to avoid a full conflict with Damascus, but many analysts have repeatedly warned that Syria’s war could increasingly impact neighboring territory.

In the town of Reyhanli on Sunday, locals were struggling to come to terms with the scale of the attack. Groups of residents loitered around the detritus of the bombs, which ripped through buildings along the town’s main thoroughfare and carved craters in the concrete. Officials said the death country may still rise.

Following the blast residents had attacked Syrian refugees and cars with Syrian number plates after the attacks, witnesses said. Additional security forces were brought from different parts of Turkey to keep the peace as groups of young men roamed the town’s main thoroughfare looking for Syrian nationals.

As the town buried their dead on Sunday, anger against Syrian refugees who had moved to the town in thousands was palpable, with hundreds of residents gathering to protest and calling for Syrians to be ejected from the town.

One woman, who earlier Sunday buried a brother-in-law killed in the blast, blamed Turkey’s prime minister for bringing Syrians to Reyhanli and demanded they leave the town. “I don’t want this government, I don’t want Syrians here. Why weren’t they taken somewhere further? They’re among us,” said the woman, who identified herself as Figen. “We are tired of seeing Syrian fighters, it was the rebels who caused this,” added a male relative, angrily.

Reyhanli is situated in a region of southern Turkey inhabited by both Turkish Sunnis and members of the Shiite-linked Alawite sect of Mr. Assad. The communities have cohabited peacefully for the last three decades, but the intensification of the Syrian civil war has put strains on that coexistence. Turkish officials have moved some Syrian refugees, most of them Sunni Muslims, away from Alawite-inhabited areas in Hatay. Syrians who opted to stay in the town on Sunday kept a low profile: one group of Syrian men said they would cross into Syria once Turkey reopened the border gate.

“For two, three days we will do our best to avoid Reyhanli residents and keep out of sight,” said Bilal Abu Daher, a refugee from the outskirts of Damascus.