A merchant vessel sighted two skiffs. First skiff approached to within 500 metres; possible weapons sighted. Vessel's armed security team fired flares and skiff moved away. Second skiff then approached to within 200m. Vessel fired another flare but there was no response from the second skiff. Vessel's  armed security team then fired two warning shots to the side of the second skiff. Skiff then broke off. Vessel is safe.