A hidden swarm of rats has been unleashed on unsuspecting Melbourne residents and businesses as major underground construction work continues.

John Govic, from Jim’s Termite & Pest Control, said the level of rat disturbance was unusual, compared to last year.

“We’ve noticed an increase of rodent activity throughout the whole season from autumn. It’s been on the increase for sure,” Mr Govic told The New Daily.

Melbourne Lord Mayor Robert Doyle said earlier on Wednesday that Metro rail tunnel construction sent thousands of “subterranean” rodents scurrying to the surface, especially during the September to November breeding season.

Mr Govic said vibrations from construction work, falling rubble and disturbed habitat would lead colonies of rats to move to street level.

“They’ve been evicted out of their homes, which is probably why a lot more people are noticing them,” he said.

“When you clear that area out, nearby areas are going to see a lot more [rat] activity. There’s nowhere else for them to go so they go to the nearest buildings they can find.”

Mr Govic said cooler spring weather meant rats were continuing to disturb residents and businesses.

“Because of low temperatures, we’ve still got an influx of calls about rats scratching walls and ceilings,” he said.

“It hasn’t dropped off yet, it’s still very intense at this stage.”

The construction site at City Square for the Melbourne Metro Rail Tunnel, viewed from Flinders Lane. Photo: ABC

The rat population would remain as it warms up, he said, but the rodents would disturb people less.

“Once the weather conditions get a bit warmer, you’ll find they tend to live outdoors more in burrows, more foliage around peoples homes, in sheds and under homes – where people don’t really notice that they’re there.”

According to figures on Weatherzone, Melbourne’s maximum November temperature has so far been 5.2 degrees below the long-term average. October was 1 degree above average.

However, Exopest owner Simon Dixon rejected the reports and said he had not seen any evidence of a rat infestation.

City of Melbourne council has hired pest control contractors to help control them.

“It’s a bit of a field day for exterminators and certainly our officers are flat out laying bait as well,” Mr Doyle told ABC Radio.

“Rats or not, you’ve still got to be humane if you are destroying them, nevertheless, you can’t have a rat plague overrunning the city, so we’ll manage it.”

The council’s multi-method baiting program, which ensures only rodents are affected, is targeting Flagstaff Gardens, Batman Park, Carlton Gardens and Fitzroy Gardens.

-with AAP