A truck driver has been caught on CCTV illegally dumping asbestos outside two pre-schools in inner Sydney.

The driver dumped two tonnes of construction waste in Wattle Lane in Ultimo in December last year.

Today the council has released CCTV footage of the "brazen and despicable" incident, appealing to the public to help find the truck and its driver.

The footage shows the truck with its tipping tray up and the rear tray gate swinging open, spilling tonnes of asbestos into the roadway as it passes over two speed bumps installed to protect pre-school children.

Director of city operations Garry Harding says the driver faces a $1 million fine and up to seven years in jail.

"The difficulty we have now is that the number is covered up, and it was deliberately covered up with a cloth," he said.

"We have some distinguishing marks on the vehicle and that's why we're appealing to the public, if they have seen the vehicle, to please come forward with that information."