British Prime Minister Boris Johnson was under increased pressure on Sunday to sack top aide Dominic Cummings who was facing allegations that he had breached coronavirus lockdown rules

for a second time.

The British government has so far rejected calls to sack Cummings over allegations he broke coronavirus lockdown rules by travelling across the country with his wife while she was suffering from symptoms of the disease, but even MPs from his own party were calling for him to leave on Sunday.

Cummings 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 day after he himself reported suffering symptoms.

Cummings strenuously denies the claims and Downing Street said late Saturday said it "would not waste time" responding to "campaigning newspapers".

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

- 'Intolerable' -

Cummings has been a highly divisive figure in British politics since masterminding the successful 2016 Brexit campaign alongside Johnson, who brought him in as his top adviser after coming to power last year.

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.

However, Tory MP Steve Baker, a staunch Brexiteer but critic of Cummings, demanded that he be sacked.

"Enormous political capital is being expended saving someone who has boasted of making decisions beyond his competence and who clearly broke at the very least the guidance which kept mums and dads at home," he wrote in The Critic.

"It is intolerable that Boris, Boris's government and Boris's programme should be harmed in this way."

His criticism was retweeted by fellow Tory MP William Wragg.

An unnamed minister earlier told the Daily Telegraph: "He's going to have to go. It's just arrogance", but Transport Secretary Grant Shapps said on Sunday Cummings would not be resigning.

Labour shadow minister Nick Thomas-Symonds told the BBC that the claims were "extraordinarily serious" and that Downing Street's denials created "more questions than answers".

- Police row -

A spokesman for the prime minister said Saturday that 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" by family, the spokesman said Saturday.

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 about a tip off they received on March 31 that he was in Durham.

The force insists they spoke to Cummings's father on the telephone, but Shapps said on Sunday that it was the family who had initiated the contact to talk about security arrangements.

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 group 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.afp