Scores of women have been invited to undergo repeat smear tests after 90 went missing en route from GP surgeries to a laboratory, it has been revealed.
The tests are thought to have left GP surgeries but never arrived at the lab, according to University College London Hospitals NHS Trust.
It apologised for any distress caused to the patients and said that anyone repeating a test would have their results "fast-tracked".
A statement said: "The trust very much regrets that a number of cervical smear test samples have been lost in transit between some GP practices and the hospital.
"Although there is every indication that the samples were sent by the practices, we have no evidence that they were received by the laboratory."
It added that all local GP practices had been asked to check that there were no other cervical smear test samples missing, and an immediate investigation has been launched by the trust in order to understand how it happened and prevent it from recurring.