Turkish security forces seized a total of 15 tons of marijuana on Friday in an operation to combat drug trafficking in the southeastern province of Diyarbakir, local newspaper Today\'s Zaman reported. Security forces carried out the operation at a location in the Lice town of Diyarbakir, said the report, adding that they also detained five suspected smugglers during the operation. The banned Kurdish Workers\' Party (PKK) is suspected to have links to the marijuana cache as drug trafficking is a major source of income for the PKK, added the report. Turkey has long been a key transit point in the drug smuggling route from Asia and Middle East to Europe. The PKK, listed as a terrorist organization by Turkey, the United States and the European Union, took up arms in 1984 in an attempt to create an ethnic homeland in southeastern Turkey. Since then, over 40,000 people have been killed in conflicts involving the group.