SOFIA, April 3 (Xinhua) -- Bulgaria seized more drugs in 2017 with heroin netted increased by 40 percent in particular, the National Customs Agency (NCA) has said.

According to the agency's latest annual report, the amount of drugs and precursors seized by the agency in 2017 reached a total of 7,572 kg, 16,128 liters and 11,699 tablets, 23 percent more than the previous year, while in precursors the increase was tenfold.

The seizures of heroin in particular increased by 40 percent to 602.6 kg, and those of opiates including heroin, morphine and opium, hit a record high for the last seven years, the figures show.

"Our success is due to the systematic and multifaceted work in recent years," Tamara Vlaykova, Spokesperson of the NCA, said in a written interview with Xinhua.

Meanwhile, the sharpened capabilities of the agency, in terms of both the personnel and equipment, also contributed to the increase.

According to the spokesperson, a good cooperation with neighboring countries, also played a positive role.

"Last but not least, we have extremely good cooperation within the European countries as well as with the neighboring countries, including Turkey, within the framework of the Southeast European Law Enforcement Center (SELEC)," Vlaykova said.

According to an unnamed NCA expert, Bulgaria is on a main land route connecting the Middle East with Central and Western Europe, also known as the Balkan Route, and the illegal trafficking of drugs, especially heroin, has been one of the main problems for the agency over the past 20 years.

In 2017, the agency found an increase in the trafficking of acetic anhydride, a critical heroin precursor, from Central and Western Europe to the heroin-producing countries, said the expert.

"In the heroin production area (Middle East), the price of this precursor has reached record levels. The profit from its trafficking is about 1,000-1,500 U.S. dollars per liter," the expert added.