A top advisor to British Prime Minister Boris Johnson faced fresh allegations Sunday that he had breached coronavirus lockdown rules for a second time.

The British government had on Saturday rejected calls to sack Dominic Cummings over allegations he broke coronavirus lockdown rules by travelling across the country while displaying symptoms of the disease.

Cummings, who announced he was suffering from coronavirus symptoms on March 30, was seen with his young son close to his parents' home in Durham, northeastern England, more than 250 miles (400 kilometres) away from his London home on March 31.

The Observer and Sunday Mirror reported that he had broken lockdown restrictions again and was seen in Durham a second time on April 19, days after he had returned to work in London following his first trip north, quoting witnesses.

Another witness told the papers Cummings was also spotted in the town of Barnard Castle, 30 kilometres from Durham, on April 12.

After defending Cummings against calls for his resignation, Downing Street late Saturday said it "would not waste time" responding to the fresh allegations.

Boris Johnson's top adviser Dominic Cummings (left) is under fire for breaking lockdown rules
Boris Johnson's top adviser Dominic Cummings (left) is under fire for breaking lockdown rules AFP / DANIEL LEAL-OLIVAS

Cummings has been a highly divisive figure in British politics ever since masterminding the successful 2016 Brexit campaign alongside Johnson, who brought him in as his top adviser following last year's election.

Under lockdown rules brought in on March 23, anyone with symptoms must self-isolate in their own homes. And people aged over 70 -- as Cummings' parents are -- are not allowed to receive visitors.

Cabinet ministers had defended his actions, with foreign minister Dominic Raab tweeting that "two parents with coronavirus, were anxiously taking care of their young child.

"Those now seeking to politicise it should take a long hard look in the mirror," he added.

After the first reports the senior aide had breached the lockdown, the opposition Labour party said Cummings' actions suggested he viewed himself as above the law.

"The public have made extraordinary sacrifices during this pandemic and the lockdown. It cannot be one rule for those who set them and another for the British people," Labour leader Keir Starmer said after reports of Cummings' first trip.

Ed Davey, acting leader of the Liberal Democrats, said if Cummings had broken the rules, "he will have to resign".

And Ian Blackford, leader of the Scottish National Party in the Westminster parliament tweeted: "It is clear that @BorisJohnson must sack Dominic Cummings."

Cummings rebuked waiting reporters for not respecting the social distancing rules
Cummings rebuked waiting reporters for not respecting the social distancing rules AFP / DANIEL LEAL-OLIVAS

An unnamed minister told the Daily Telegraph: "He's going to have to go. It's just arrogance."

But a spokesman for the prime minister said Cummings had acted "in line with coronavirus guidelines.

"Owing to his wife being infected with suspected coronavirus and the high likelihood that he would himself become unwell, it was essential for Dominic Cummings to ensure his young child could be properly cared for," the spokesman said Saturday.

"His sister and nieces had volunteered to help so he went to a house near to but separate from his extended family in case their help was needed," he added.

Deputy chief medical officer Jenny Harries suggested there was some room for manoeuvre if both parents were ill, saying "all guidance has a common sense element to it, which includes safeguarding around adults or children".

Cummings also denied reports in The Guardian newspaper that police had spoken directly to him or his family over the issue.

Nevertheless, police in Durham had confirmed on Friday that they received a tip-off on March 31 about someone who had travelled to the city from London.

"Officers made contact with the owners of that address who confirmed that the individual in question was present and was self-isolating in part of the house," the police said.

Cummings on Saturday told a throng of reporters while leaving his house that it was "a question of doing the right thing, it's not about what you guys think", while rebuking the grounp for not obeying social distancing rules.

Downing Street revealed at the end of March that Cummings was self-isolating with virus symptoms. Johnson was also infected and ended up in intensive care.

Earlier this month, leading epidemiologist Neil Ferguson quit a government panel on coronavirus after admitting breaking the lockdown rules by meeting his mistress.

Britain has been the worst hit country in Europe, with a death toll of 36,675, up 282 in the last 24 hours.