In a letter published by TheTimes, the chancellor warned the prime minister Britain’s border rules were damaging the economy, and tourism in particular.
It comes ahead of a "crucial" meeting of ministers on Thursday (5 August), which will – reportedly – determine the travel rules for August.
In the letter, Sunak said the UK’s border policy was "out of step with international competitors" and voiced particular concern about the tourism and hospitality sectors.
According to reports, a source close to Sunak said: "Rishi has called time on the travel restrictions."