“We are focusing on migrant workers because of the surrounding witnesses and evidence, including the video footage,” senior police official Maj Gen Kiattipong Khawsamang said.

The bodies of Hannah Witheridge, 23, and David Miller, 24, were discovered in the early hours of Monday morning on the island of Koh Tao.

Police believe the pair were attacked with a hoe and have today released still images from CCTV footage in the area, one of which shows a man – of Asian appearance – who police believe is the prime suspect.

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