KIEV (AFP) - Ukraine police seized heroin worth about US$60 million (S$81 million) - over half a tonne of the powder - in raids in the country's centre and west, officials said on Sunday (March 31), describing it as the biggest haul they had ever seen.

Chief of the national police Sergiy Knyazev announced on Facebook two raids in the Kiev region yielding "600kg of heroin worth $50 million".

About 500kg were found on Sunday afternoon, and more than 100kg overnight "in a professionally equipped cubby hole in a premium-class car" outside Kiev.

"I have never seen so much heroin seized by the Ukrainian police," Mr Knyazev said.

"Four people were detained: a citizen of Moldova, Turkey and two from Macedonia," he added.

In a separate investigation, officials found "almost 130kg of heroin worth US$10 million" at a house in a village in the western Transcarpathia region, Ms Larysa Sargan, spokesman for the Prosecutor-General wrote on Facebook.

The European Monitoring Centre for Drugs and Drug Addiction says Ukraine is a transit country for heroin trafficked from Afghanistan to western and central Europe, mainly via the North Black Sea route and from Russia.

"The trafficking of illicit substances is facilitated by a large international transport network (roads and trains) that connects Ukraine to the east and west, and by the presence of several international ports that link Ukraine to the Balkan Route," according to a country overview on the agency's website.

"In recent years, the smuggling of psychotropic substances via international postal services has also increased," it says.

On March 21, Ukraine's SBU security service seized cocaine worth about US$51 million in a South American cargo ship that docked in the Black Sea port of Odessa.