Free lateral flow tests might not be approved in time for those going on holiday when the borders re-open in a week, it has been claimed.
This would mean a family of four would be faced with paying up to £320 on departure and return for PCR tests to travel to green list countries.
As of next Monday, holidaymakers can travel to 12 destinations, including Portugal, Gibraltar and Iceland, without having to quarantine for 14 days on return to England.
They will, however, still be required to take one pre-departure and one post-arrival Covid test which the UK Government had suggested would be provided free to avoid having to purchase one while abroad.
But due to concerns about the effectiveness of the fast turnaround tests, Downing Street has failed to reach a "cross-Government agreement", it has been claimed by sources.
It is understood some officials fear the scheme may not be as straight forward as was hoped on paper, with issues around validating the self-administered test results and their accuracy.
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Transport Secretary Grant Shapps had been due to announce the test kits on Friday during the briefing which saw the traffic light system laid out.
Without them, people travelling abroad from next week will have to shell out up to £20 for their first test and £60 for a second PCR test after returning home in the UK.
Guidelines stipulate a certain level of accuracy in testing, which the more expensive PCR tests are deemed to meet but which there are still some doubts about in relation to the lateral flow alternative.
The average sensitivity of flow testing for identifying those with the virus is 76.8 percent while the Government requires accuracy of more than 80 percent.
A source told the Daily Telegraph : “It is more about the implementation than the science. How do you check the results? How do you validate them? Do people just turn up and show them?”
A DfT spokesman told the newspaper it was “working with the travel industry and private testing providers ahead of international travel reopening, to see how we can further reduce the cost of travel for the British public, while ensuring travel is as safe as possible".
A Department of Health spokesman added: "This could include cheaper tests being used when holidaymakers return home, as well as whether the Government would be able to provide pre-departure tests."
