Giant 'super' rats that are resistant to poison are spreading across the UK at an alarming rate, says a new report.
Scientists who are monitoring their invasion of communities in 17 counties in the UK found that every rat tested was immune to conventional poison, reports the Daily Mail, .
Counties that have been 'invaded' so far include Berkshire, Suffolk, Surrey, Wiltshire, Hampshire and Kent.
The Tonight programme will show footage and images of these 'super rats' tonight (Thursday) on ITV at 7.30pm.
Researcher Dr Dougie Clarke said: "I think people should be concerned about these resistant rats because of public health... they carry disease and various other bacteria and viruses.
"They also damage buildings...they cost billions of pounds of damage worldwide."
While the rats have been growing and changing, humans have been using the same anticoagulant rat poisons since the 1950s.
"With the use of rodenticides, normal rats are killed off, and then the resistant ones remain," says Dr Clarke.
"So it's a sort of time bomb of resistance building up over generations of rats."
He added: "We've tested 17 counties and every single one of them has got resistant rats - this was an amazing find to us. We didn't expect to have every single county to have resistant rats."
Back in April, it was reported that enormous 'mutant' rats had made their way north from London and Birmingham to Liverpool.
The huge 'super rats' have been spotted across Merseyside.
Sean Whelan, of Whelan Pest Prevention, told the Liverpool Echo: "All around Merseyside there's been a problem.
"We're seeing bigger rats in Liverpool. They're super rats in my opinion."
Daily Telegraphreports that a study from the University of Huddersfield in 2009 suggested that genetic mutations had produced a new breed of 'super rat' in Britain with DNA that was resistant to standard poison.
Pest controllers are now looking at a new, stronger type of poison to control the problem. But it would require permission from the Health and Safety Executive.
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