Hygiene standards at a hospital have been criticised by a microbiologist who said they are worst he has seen.
Professor Pennington said the dirt was putting lives at risk
Professor Hugh Pennington said secretly filmed footage by the BBC led him to believe lives were being put at risk on the wards.
The film shows overflowing bins and a bloodstained gown left on a theatre trolley at the Kent and Sussex Hospital in Tunbridge Wells.
The hospital said its in-house cleaning service was being improved.
Professor Pennington said BBC South East Today's footage, filmed by a journalist working undercover for the hospital-managed cleaning service, revealed "inexcusable" practices.
He said the hospital, which is used by people living in north Sussex and west Kent, was not even clean by domestic standards.
At one point during filming, the accident and emergency department almost ran out of paper towels - vital to dry hands after washing to prevent spreading infection.
Prof Pennington compared being so short of hand towels to running out of anaesthetic gas during an operation.
The University of Aberdeen professor also criticised medical staff for leaving used instruments in an operating theatre sink for seven hours and a bloodstained gown on a trolley for 24 hours.
After watching the film, he told BBC South East Today: "It's been scandalously easy to find major deficiencies in this hospital.
"It's a dirty hospital, it's the worst I have ever seen.
"It's putting the lives of patients and staff at risk."
Rose Gibb, the newly appointed chief executive of Maidstone and Tunbridge Wells Trust, was shown the footage.
In response she said: "The hospital has got cleaning problems, I've been aware of those for the last six months.
"I've put a massive amount of improvements into them, and I'm going to continue to put improvements into the hospital until we get it to the level we want it to be.
"There are particular issues at the Kent and Sussex that are not found elsewhere.
"It's cramped, it's overused, the fabric is appalling, there's next to no storage facilities, and staff are working in unacceptable conditions."
Miss Gibb said it would take nine months to get the service to a high standard.
The BBC South East Today Undercover report can be seen on BBC One on Monday at 1830 BST or for viewers outside the south east region on digital channel 953.