Mutant rats which are apparently immune to poison are invading homes across south-east London, to escape the heavy rain storms.
Rats have been entering houses through small gaps and travelling up drainpipes to escape the hazardous conditions outside.
The creatures have built new homes in lofts, within the walls of properties and other warms areas of homes.
They are known to carry diseases such as Weil's Disease (Leptospirosis), a bacterial infection which can eventually cause meningitis, liver damage and renal failure. The rats can grow up to 25cm in length and a single pair can produce 200 offspring in one year.
Rentokil, the pest controller, reported on its websites that the mammals were seeking shelter from the stormy conditions and rising water levels.
It read: "Rodents have also had to abandon their homes as rivers overflow their banks, sewers flood and allotments, parks and other grounds become waterlogged.
"Rats are forced to vacate flooded and damaged burrows in search of new, drier harbourages. These can include homes, outbuildings, compost heaps or factory buildings."
With more storm warnings in place, the problem is expected to get worse. Heavy rain and strong winds are expected to batter the south of Britain, leading to further risk of flooding.
In the next few days, a weather system developing off the Atlantic is set to sweep across the UK, delivering a deluge of rain on Friday night. Gale-force winds, of up to 80mph, are also expected to cause extreme damage to properties and transport links as well as bringing down trees.
To reduce the risk of rats entering homes, a spokesperson from the Chartered Institute of Environmental Health advised that food is disposed of properly, to discourage the rodents. They also suggested blocking visible holes, as rats are "intelligent, adaptable creatures" that "exploit new opportunities".