Turkish authorities have arrested a group of Syria's al Qaeda-linked al-Nusra Front militants who allegedly had been planning an attack inside Turkey and were in possession of the nerve agent sarin, local media reported on Thursday.
While they could not be immediately confirmed, the reports highlight the growing concerns that Syria's civil war is dragging in neighbouring states.
In the worst example of the spillover into Turkey, 52 people were killed when twin car bombs ripped through the border town of Reyhanli on May 11. Turkey has accused Syria of involvement in the attacks, but Damascus has denied any role.
The 12 Nusra members were arrested in the southern city of Adana, some 100 km (60 miles) from Syria, during raids at their addresses where police uncovered 2 kg (4.5 pounds) of sarin as well as heavy weapons, Taraf, Cumhuriyet and Aksam, as well as several other dailies reported.
The men, who were allegedly planning a large attack in the city, were formally detained by Adana's top court, the papers reported, although it was not clear on what charges. The papers did not reveal their sources.
Adana's police department said it had not heard of the reports and the governor's office could not be reached for comment.
Nusra is one of the most effective forces fighting President Bashar al-Assad and last month pledged allegiance to al Qaeda leader Ayman al-Zawahri. The U.S. State Department designated Nusra as a terrorist organisation in December.
Experts have long said Nusra is receiving support from al Qaeda-linked militants in neighbouring Iraq. The group claimed responsibility for deadly bombings in Damascus and Aleppo, and its fighters have joined other Syrian rebel brigades.
Assad's forces and opposing rebels have accused each other of using chemical weapons, and both have denied this.
The United States has said it views any use of chemical weapons in Syria as a "red line", hinting this could lead to some form of foreign intervention. But chastened by the false intelligence that was used to justify the 2003 war in Iraq, Washington says it wants proof before taking any action.