Bulgarian customs officials say they have seized 288 kilograms (635 pounds) of heroin found in an Iranian truck entering Bulgaria from Turkey.

The drugs were discovered at the Kapitan Andreevo checkpoint, customs officer Ivan Kuchmov said on Friday. They were stashed in 144 packages hidden inside the officially declared machinery transported in the truck.

The Iranian truck driver and a Turkish citizen suspected of being the recipient of the drugs in Bulgaria were detained and could face up to 20 years in jail if convicted on drug trafficking charges.

Bulgaria, which lies on a drug route from the Middle East to Western Europe, has taken massive steps in the past couple of years to prevent drug trafficking.

In 2018, Bulgarian customs officers confiscated a total of 1,021 kilograms (2,250 pounds) of heroin at the country's borders, almost 20 percent more than in the previous year.