The UK's coronavirus testing chief has urged the public not to buy off-the-shelf DIY antibody tests.
Professor John Newton told the Commons Science and Technology Committee the public should wait for approved home tests which are currently being trialled.
The Government announced on Thursday that more than 10 million antibody kits were being bought for use in hospitals and care homes.
But high street chains including Superdrug have started to offer a home antibody test kit for £69.
When asked about the new home tests, Prof Newton said better tests would be available to the public soon.
He said: "The public need to be aware that those tests are not the same as those we have evaluated and approved for use."
He added: "The laboratory-based tests have a much higher standard of accuracy.
"We wouldn't recommend at the moment that people rely on the tests that are becoming widely available.
"My advice would be to wait until we have better tests which will be available in a similar form very soon, though they are still under evaluation at the moment."
His comments echo those of NHS medical director Professor Stephen Powis who said earlier in the week people should be cautious over buying home kits.
Professor Newton also revealed up to half of all at-home antigen tests - which show if a person currently has the virus - have not been returned.
Asked at the committee what proportion of the kits are returned, Professor Newton said he did not have a figure, but estimated that it was "more than half."
"To begin with, a relatively... I think something like... certainly more than half. We would like to get that amount up," he said.
He added: "I'm afraid I don't have that figure, but it can be provided by the programme, I'm sure."
