A man who was caught riding a children's scooter through the Cross City Tunnel in Sydney has been fined $71.

The 42-year-old was filmed riding the scooter through the tunnel yesterday about 3:30pm.

The man then turned himself in to Surry Hills police station and admitted he was the person in the video, after the footage was broadcast on several media outlets.

Police said in a statement the incident was a reminder for all drivers to act safely on the roads.

"Regardless of how the person came to be in the tunnel, their safety was at risk and there was potential for him to be hit or to cause a crash," Acting Assistant Commissioner Smith said.

A spokesman for the Cross City Tunnel said the man forced several cars in the tunnel to slow down behind him, prompting warnings from staff.

By the time crews had arrived, the man had already left the area.

Under NSW law, all foot scooters, skateboards and rollerblades are illegal to use on roads with speeds greater than 50 kilometres per hour or on any one-way road with more than one marked lane.