Blair was pictured leaving a restaurant in London some 10 days after returning from a two-day trip to Washington last month, Britain's Sunday Telegraph reports.

The former UK prime minister had asked government officials for exemption from the rules, but was not issued with a formal letter which would have allowed him to avoid the two-week quarantine, according to the newspaper.

But a spokeswoman for Blair said the former leader was told to follow guidance on international conferences, having been invited by US officials to attend a White House event on the Israel-UAE peace deal.

"He was not refused exemption by the UK Government," the spokeswoman said.

"He was told to follow the guidance on international conferences which he did; the US Government had cleared the visit because it was for the diplomatic conference at the White House.

"We believe he followed all UK and US government guidelines as advised.

"Mr Blair was tested for COVID before departing the UK, on arrival at the White House, when he returned to the UK and has been tested several times since."

The spokeswoman said all COVID-19 tests were negative, and Blair did not attend any other meetings during his trip.

Government guidance states that diplomats and representatives at international conferences are granted "privileges and immunities", meaning they are not required to self-isolate if their work is confirmed as essential.

Conservative MP David Jones told the newspaper it was hard to see how Blair could rely on claiming he had been tested "when we haven't got a testing regime".

"It sets an appalling example to travellers if a former prime minister appears to flout the rules in such a flagrant manner," he said.

Australian Associated Press