Dominic Cummings has the "full support" of the Prime Minister after details emerged that he travelled 250 miles to County Durham during the lockdown.

Boris Johnson had come under pressure to sack his top aide after it was revealed he drove his wife and child from their London home to a family property in the North East after his spouse developed coronavirus-related symptoms.

Transport Secretary Grant Shapps, speaking at the daily Downing Street Covid-19 briefing, said: "I can tell you the PM provides Mr Cummings with his full support."

Number 10 had already offered the former Vote Leave campaign mastermind its support when putting out a statement on Saturday, stating that Mr Cummings' actions "were in line with coronavirus guidelines".

But Mr Shapps' latest comments are an indication that the PM is sticking by the controversial figure, who he credited with helping secure him his landslide election victory in December.

The SNP had been calling for the Conservative Party leader to sack Mr Cummings, with the party, along with Labour and the Liberal Democrats, having written to Cabinet Secretary Sir Mark Sedwill demanding an inquiry into what happened.

According to a joint investigation by the Guardian and Daily Mirror, Mr Cummings was spotted twice in the North East over the course of almost a week, between March 31 and April 5.

Number 10, in its statement on Saturday, confirmed the 48-year-old had not yet started displaying Covid-19 symptoms when he drove to Durham, but did so in the "high likelihood" he would contract it and need childcare for his four-year-old son.

Deputy chief medical officer Dr Jenny Harries said travelling during the lockdown could be justified if there was an "extreme risk to life".

Asked if Mr Cummings' actions undermined the "stay at home" message that was first promoted by the UK Government, Dr Harries refused to comment on the specific incident.

She told the press conference: "In relation to the advice to the public, it's absolutely clear that public health guidance is, if you're symptomatic you stay at home, take yourself out of society as quickly as you can with your family and stay there, unless there is extreme risk to life."

Mr Cummings, speaking to reporters outside his London home on Saturday, said he had acted "reasonably and legally".

When a reporter suggested to him outside his London home that the trip to Durham did not look good, he replied: "Who cares about good looks?

"It's a question of doing the right thing. It's not about what you guys think."

Durham Constabulary said it contacted Mr Cummings' family after reports he had been sighted in the area, but No 10 denies that version of events.

In a statement, a No 10 spokesman said: "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.

"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.

"His sister shopped for the family and left everything outside.

"At no stage was he or his family spoken to by the police about this matter, as is being reported.

"His actions were in line with coronavirus guidelines. Mr Cummings believes he behaved reasonably and legally."

Durham Constabulary said in a statement on Friday that officers contacted the owners of a property on March 31, more than a week after the lockdown had been imposed by the PM, when they were made aware of reports that an individual had travelled from London.

Speaking on Friday, a spokesman for the force said: "On Tuesday, March 31, our officers were made aware of reports that an individual had travelled from London to Durham and was present at an address in the city.

"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.

"In line with national policing guidance, officers explained to the family the arrangements around self-isolation guidelines and reiterated the appropriate advice around essential travel."

The force declined to update its statement after the Downing St comment. But Durham Police and Crime Commissioner Steve White said officers "acted appropriately".

Mr White, the former head of the Police Federation in England and Wales, said it was "most unwise" for the Downing Street adviser to have travelled when "known to be infected".