Ethnic Albanian criminal gangs continue to pose a serious security threat, dominating the transit and supply of heroin to Switzerland, warns a federal police expert. Three members of the same Kosovo family are currently on trial in Switzerland accused of operating one of Europe's largest heroin wholesale operations. Prosecutors say the 69-year-old father and his two sons, aged 42 and 28, used their base in the southeast European country to import 1.5 tons of heroin from Turkey for sale elsewhere. "[The clan] has been one of the principle suppliers of heroin in western Europe since the middle of the 90s," the prosecution claimed. The defendants deny all charges. They went on trial in Switzerland because the brothers lived and worked there. A verdict by the Federal Penal Court in Bellinzona is expected at the end of October. According to Roger Flury, an illegal drugs expert at the Federal Police Office, the seizure was very significant, even though it was split between different countries. "1,500 kg - that's between 25 to 50 percent of what people consume in Switzerland in one year," he told swissinfo. Significant threat In its 2007 internal security report published in July the federal police said that "criminal organizations from southeastern Europe" played a "significant role" in Switzerland. These internationally interlinked groups were involved in numerous criminal activities including drug and human trafficking, migrant smuggling, ...