Substandard surgical tools from Pakistan are putting UK patients at risk of potentially deadly injury and infection, BBC Panorama has found.
Faults include rough edges, steel burrs that can splinter during operations and corroded metals.
All surgical instruments have to meet regulatory standards but only one of the more than 180 NHS trusts and boards conducts rigorous tests on every tool.
Barts and the London NHS Trust reject almost 20% of tools as unsafe for use.
Tom Brophy, the dedicated technologist at Barts, said the prevalence of faulty equipment that could endanger patients' lives or cause serious injuries is so worrying that he has started documenting the faults.
While he is able to return unsuitable or faulty tools to suppliers, he said there is nothing to stop those same instruments from being sold on to another UK hospital, either within the NHS or private.
"On more than one occasion a supplier has rung me up and said that the instrument you rejected, I passed it onto another hospital and they accepted it," he said. "Of course they're going to accept it, because they haven't checked it."
Two-thirds of the world's surgical instruments are made in the city of Sialkot in northern Pakistan and 70% of the UK's registered manufacturers are based in the city.
While some of the larger companies operate state-of-the art facilities and have rigorous quality-control procedures in place, Panorama found evidence of smaller firms that do not use magnifying glasses to inspect finished instruments before putting the required quality stamp on them.