China Coast Guard vessels on Wednesday evening began shadowing a convoy of Filipino civilian boats on their way to the contested area of Scarborough Shoal, also known as Panatag Shoal, a spokesman of the Atin Ito convoy said. Three clearly marked China Coast Guard vessels sailed within sight of the convoy at dusk and broadcast radio warnings heard aboard one of the Philippine boats as the Atin Ito flotilla moved closer to Panatag Shoal, convoy spokesman Emman Hizon said.