A large lizard on track halted final practice for the Singapore Grand Prix on Saturday as Formula One marshals tried to catch the rogue reptile.

Drivers watched in amusement as the monitor lizard reacted to the chase with a sudden burst of speed after sauntering onto the circuit shortly after the start of the daylight session. The lizards are a familiar sight in the Lion City.

Aston Martin's Fernando Alonso, with team mate Lance Stroll the only drivers on track at that time, was alerted to the lizard's high-risk walk in the final sector.

"We are told the track is clear but just have a look for the lizard," the Spaniard was told over team radio.

"No, it's in the middle of the track," the double world champion replied as he skirted it and returned to the pit lane.

Sky television commentator David Croft named it Larry, suggesting it had the purposeful stride of Aston Martin team owner Lawrence Stroll.

The interruption was brief before practice resumed.

Lizards have been a regular hazard at the grand prix, with Max Verstappen's Red Bull race engineer Gianpiero Lambiase dubbing one particularly large specimen "Godzilla" in 2016.

When a smaller one emerged during last year's practice, Lambiase suggested "maybe Godzilla had a kid".

Monitor lizards are typically shy, according to Singapore's National Parks' Board, unless cornered. They are also diurnal, meaning they sleep at night – a relief for organisers of the night race. (Reuters)