A police standoff is underway on Melbourne’s Bolte Bridge after a graffiti vandal drew a large Pam the Bird on one of the structure’s two concrete towers.

The individual was spotted scaling the 140-meter-tall concrete tower in the early hours of Tuesday morning, before drawing the infamous Pam the Bird symbol.

Victorian police are on scene and have closed one of the bridge’s southbound lanes.

“A man has scaled the bridge and remains in a restricted area on the eastern tower,” a Victoria Police spokesperson said.  

The spokesperson said the man was “refusing to follow police direction and come down”.

“There are a significant number of police resources in the area including uniform members and water police units,” police said.

“Police are currently working to get the man down safely.”

VicTraffic said speeds on the bridge had been reduced to 40km/h as the incident unfolded.

“The left lane is closed inbound over the Bolte Bridge due to a trespasser,” an alert said. 

“Speed reduced to 40km/h. Allow extra time citybound over the bridge.”

Pam the Bird has become an infamous graffiti symbol appearing in locations across Melbourne.

Last year, police alleged a 21-year-old man was responsible for the Pam the Bird graffiti. 

He was charged with more than 50 offences, including spray painting the symbol on Melbourne landmarks such as Flinders Street Station.

It is not clear whether the individual atop the Bolte Bridge tower on Tuesday is the same person.