Nigel Farage has been reported to police after apparently visiting a pub less than a fortnight after a trip to the American city of Tulsa.
Everyone returning from abroad is supposed to self-isolate for 14 days under the current quarantine laws.
Yesterday the government announced the restrictions would be lifted for some countries, but only from 10 July.
The former Ukip leader Mr Farage was pictured on social media earlier today as pubs opened for the first time since lockdown in March.
Liberal Democrat acting leader Sir Ed Davey has now written to Kent Police asking them to investigate if Mr Farage has breached quarantine rules.
He said it was the responsibility of everyone to take lockdown requirements seriously.
“By choosing to go to the pub when it appears he should have been staying at home, Mr Farage is showing a flagrant disregard for the safety of people in his community.”
Mr Farage later took to Twitter to say he had been in the UK for two weeks.
He wrote: “To all those screaming and shouting about me going to the pub.... I have been back from the USA for 2 weeks and I have been tested — the result was negative. Sorry to disappoint you. Cheers!”