The government has denied that travellers from France will be exempted from the planned coronavirus quarantine measures.
Under the plans announced last weekend, people arriving from abroad must isolate themselves for two weeks.
Those with nowhere to stay will be obliged to isolate in accommodation provided by the authorities.
Initially, a joint statement from the British and French governments said no quarantine measures would apply.
"No quarantine measures would apply to travellers coming from France at this stage; any measures on either side would be taken in a concerted and reciprocal manner," says the statement, which was published on the government's website on 10 May.
"A working group between the two governments will be set up to ensure this consultation throughout the coming weeks."
The policy attracted a warning from the EU not to single out one nation, while some experts suggested it would prove unworkable.
But today, the prime minister's spokesman insisted there was no French exemption, and that the original statement referred to the need for cooperation to manage the common border between the two countries.
It now appears that those exempted from the policy could include freight drivers, in order to allow the flow of goods to continue, and people working on Covid-19 research, but not ordinary travellers.
The government had already indicated that people arriving from the Republic of Ireland will not be made to go into quarantine, an arrangement that will be unaffected by today's news.
However, the measures will apply to UK holidaymakers returning from other destinations.
In his address to the nation on Sunday, the prime minister said: "I am serving notice that it will soon be the time - with transmission significantly lower - to impose quarantine on people coming into this country by air."
The government later clarified that the rules would apply not just to air passengers, but also those arriving by other means of travel such as train or ferry.
Following Mr Johnson's speech, No 10 confirmed a reciprocal deal with the government in Paris meant restrictions would not apply to passengers from France, but that was ahead of today's apparent u-turn.