Thousands of testing kits posted to people's homes have not been sent back, the Government's testing coordinator has admitted.

Some 762,252 tests have now been posted to people's homes but Professor John Newton said not all had been returned for analysis.

He told the Science and Technology Select Committee more than half had been returned, but he did not have an up-to-date figure.

He added: "I think certainly more than half, and we would like to get that amount up.

"A lot of the ones which were counted as they left were not home tests, they were the satellite tests sent out to care homes."

When pressed on the current return rate, he said he would provide it to the committee after the session.

Prof Newton added: "I am afraid I don't have that figure but it can be provided."

The Government managed to hit its 100,000-a-day testing target but only by counting kits sent out, rather than only including completed tests.