No details of the four individuals have been released, but efforts to trace their sexual contacts to offer them HIV tests are now under way.
The confirmation of the false negatives follows the re-analysis of more than 20,000 blood samples tested for HIV between July1995 and March this year, with the IMX HIV 1/2 3rd generation kit.
Sir Kenneth Calman, the Chief Medical Officer, said in a statement: "I would like to extend my sympathies to [the four] individuals in what must be a very difficult situation."
The IMX kit, one of several used by the NHS, was withdrawn from sale worldwide on 25 March by its manufacturers, Abbott Laboratories of Chicago, after some reports of inaccurate results.
News of the kit's withdrawal was leaked at the start of the Easter bank holiday when clinics and GP surgeries were closed, leaving thousands of people desperate for more information and advice.
The Department of Health said that since July last year a total of 23,620 blood samples in the UK had tested negative using the IMX kit. All available stored samples - 20,900 - had been re-tested and four of the negative results found to be wrong. Stored samples were not available to re-test the remaining 2,720. About 800 of these were done in NHS clinics and the people concerned had been invited to provide fresh samples. The other 1,920 were provided for private tests, mainly for insurance purposes.Reuse content