ANKARA (AFP) - Turkey has revoked a contract to purchase six billion cubic metres a year of natural gas from Russia, its main supplier, after failing to win a discount, Energy Minister Taner Yildiz said Saturday. The contract on the western routing has been wound up because the request for a lower price has been refused, Anatolia news agency quoted him as saying. Yildaz had threatened Thursday to end the contract under which Turkey imports gas from Gazprom Export, a subsidiary of the Russian gas giant Gazprom, via a pipeline passing through Ukraine, Romania and Bulgaria.