A couple of scaly guests made an unexpected appearance at a Formula One practice session in Singapore on Friday, much to the bemusement of drivers and onlookers.

In videos posted to the official Formula One channel on YouTube and X, formerly known as Twitter, a monitor lizard was seen ambling across the tarmac at the Singapore Grand Prix, with drivers weaving around the large reptile and officials waving yellow flags to signal the potential hazard.

"It's going to be a brave marshal to go out and pick one of those up," Red Bull team boss Christian Horner told Sky Sports television according to Reuters. "Hopefully they'll be going to bed soon."

Minutes later, a second lizard entered the fray, seemingly unbothered by the roaring engines.

"Ah, there's a lizard again on the track, a smaller one this time," Dutch world champion Max Verstappen exclaimed over the radio.

"Maybe Godzilla had a kid," a race engineer replied.

Verstappen was seen swerving to avoid the creature, his second encounter with them on the track since 2016.

Mercedes' George Russell and Ferrari's Carlos Sainz were also heard shouting out about the lizards on radio.

One lizard met a grisly end when it appeared to have been run over by one of the cars, reported Singapore's Straits Times newspaper.

Water monitors are a large breed of monitor lizard and are a common sight in Singapore's green spaces and rivers. The reptiles can grow to as long as two meters in length (6 feet) and weigh up to 19 kilograms (43 pounds).