Detectives have released CCTV footage of a man seen near two luxury boats before they were engulfed in flames at a Sydney wharf.

The boats collectively worth $2 million were destroyed on Saturday morning in a suspected arson attack at Woolloomooloo's Finger Wharf.

Police want to speak to a man captured in CCTV footage walking up to the moored cruiser and yacht before the back of one boat is ignited.

The man then heads back towards the footpath, climbs through a gate and walks slowly away.

The man then heads back towards the footpath, climbs through a gate and walks slowly away. Photo: NSW Police

The two 40-foot vessels were destroyed by the fire and ended up on the bottom of the harbour.

The boats were salvaged on Monday and will undergo further examination.

Detectives believe the fire was deliberately lit.

On Saturday they spoke to a 24-year-old man about the blaze, who was arrested for unrelated property offences, but he was released without charge.

Police are urging anyone with information in relation to this incident to call Crime Stoppers on 1800 333 000 or use the Crime Stoppers online reporting page: https://nsw.crimestoppers.com.au/