All coronavirus tests are to be turned around within 24 hours by the end of June, the Prime Minister has said.
But speaking in the Commons Boris Johnson said the target would need to take into account “insuperable problems” such as postal delays.
The 24 hour target was announced on 27 May, but no deadline was set.
The head of the testing service has said 84% of drive-in centre tests come back within a day – but no equivalent figure has been provided for home kits.
Questioned on the Test and Trace programme during Prime Minister’s Questions by Jeremy Hunt, chair of the Health Select Committee, Mr Johnson said: “I can undertake to him now to get all tests turned around in 24 hours by the end of June, except for difficulties with postal tests or insuperable problems like that.”
Last week the head of England’s testing programme, Dido Harding, said 84% of tests at drive-in centres were returned within 24 hours, and 95% within 48 hours. No figure was provided for home testing kits, or those provided at other settings.
The programme means anyone with a positive coronavirus test will be contacted to report their recent encounters with people, and places they have visited.