ANKARA: Turkish security forces arrested Monday four Syrians linked to President Bashar al-Assad's regime over a deadly bomb attack on the volatile border last month, the interior minister said.

"Our security forces arrested four Syrian nationals and one Turkish citizen" over the minibus bombing which killed 14 people, Muammer Guler said in televised

remarks. "We proved their links with the Syrian intelligence and army."

He said three other suspects who were previously arrested in connection with the attack were released and one other suspect was at large.

The minibus exploded in the buffer zone between Turkey's Cilvegozu border crossing and Syria's Bab al-Hawa post on February 11, the latest spillover of violence from Syria's civil war.

The Cilvegozu crossing is one of seven functioning border posts along Turkey's 910-kilometre (560 mile) frontier with Syria.

It is a major gateway into Syria, with hundreds of trucks lining up every day to take humanitarian aid into the war-torn nation.

Turkey, a one-time Syria ally now vehemently opposed to Assad's regime, has taken in some 190,000 refugees registered in several camps along the border and 100,000 more across the country, according to foreign ministry figures.

Five Turkish civilians were killed in October when shells fired from Syria landed in border areas, which exacerbated tensions between the neighbours.

Turkey has systematically fired back after every cross border shelling since then and scrambled jets along the border in a warning to the Damascus regime not to breach its territory.

NATO approved in December the deployment of six batteries of US-made Patriot missiles near the border, saying the use of ballistic missiles by the Syrian regime posed a threat to Turkey.