SOFIA, Feb. 25 (Xinhua) -- Bulgarian customs have seized 35 kg of ecstasy at the country's Kapitan Andreevo checkpoint near the border with Turkey, the Prosecutor's Office said in a statement on Monday.

The illicit drug, split into 18 packets, was discovered on Thursday in a Turkish bus traveling from Romania to Turkey via Bulgaria, the statement said.

The packages were hidden in the cavities of the bus and was scheduled to be transported to Istanbul, the statement said.

The investigation has found that one of the bus drivers had taken the shipment on the territory of Bulgaria, it said.

Authorities estimated the value of the drugs on the black market would exceed 720,000 U.S. dollars.

The driver, a 43-year-old Turkish citizen, was arrested at the scene, the statement said.

Ecstasy, or methylenedioxy-methamphetamine (MDMA) is a synthetic drug that alters mood and perception.