Police hunt severely burned arsonist after restaurant attack

Police believe one of the arsonists behind the overnight attack on a popular Melbourne restaurant may have seriously burned themselves in the process.

CCTV has been released which shows a pair dressed in balaclavas and jumpsuits smashing their way through a door at Republica on the St Kilda foreshore overnight.

Armed with a jerry can full of accelerant, the men can be seen on camera dousing the main dining area and bar at about 4am.

One of the men appears to struggle to ignite the fluid as he crouches down close to light it, but when he does it explodes and quickly spreads throughout the restaurant.

Police told 9NEWS it was a reckless act.

"It could've had more dire results," Sergeant Peter Tasiopoulos said.

Owners Matt Dawson and Tom Doolan arrived to find their restaurant a charred mess.

It follows another attack on November 13, when three men threw petrol bombs into the restaurant, causing hundreds of thousands of dollars in damage.

"We've had both the last incident and we're about to have this incident examined by forensic experts," Sergeant Tasiopoulos said.

However police and management at St Kilda Seabaths have played down suggestions of involvement by bikie gangs.

Republica's "house rules" stipulate gang colours are not allowed at the venue, and several gang members have caused problems at the venue in recent times.

Forensic police have spent the day collecting evidence, including a melted jerry can.

The damage bill is expected to total almost $1 million without factoring in the lost Christmas trade.