British Prime Minister Boris Johnson is under renewed pressure to sack his closest aide Dominic Cummings after eyewitness reports called into question both Mr Cummings' and Downing Street's account of his lockdown whereabouts.

Mr Johnson had offered his "full support" to his under-fire chief adviser after it emerged Mr Cummings had travelled 400km to Durham, despite strict restrictions at the time not to journey long distances.

Mr Cummings, in a statement issued through Number 10, said he travelled to be close to family to seek help looking after his four-year-old child after his wife became ill with coronavirus symptoms.

But fresh claims, according to reports in the Observer and Sunday Mirror newspapers, suggest the 48-year-old made a second trip to Durham, having been spotted in the region on 19 April - five days after returning to work in Westminster and while strict rules were still in place not to travel.

A second eyewitness told the two papers they also saw him a week earlier in Barnard Castle on Easter Sunday, a popular tourist location 30 miles away from Durham.

The news comes after a host of senior Cabinet ministers - including Health Secretary Matt Hancock and Attorney General Suella Braverman - took to social media to show support for Mr Cummings.

Transport Secretary Grant Shapps, speaking at the UK government's daily coronavirus briefing, said Mr Cummings had "stayed put for 14 days" while residing at a family property, having pre-empted his own illness once his wife showed Covid-19 symptoms.

But the trip to Barnard Castle, if correct, would call that testimony into question.

Ian Blackford, leader in Westminster of the SNP, renewed his calls for Mr Johnson to axe Mr Cummings from his team following the new reports.

He wrote on Twitter: "It is clear that Boris Johnson must sack Dominic Cummings.

"When the PMs top advisor ignores the Government's instruction to the public not to engage in non-essential travel he has to leave office. Immediately."

A UK Labour source questioned why senior ministers had defended Mr Cummings in light of the fresh allegations.

Culture Secretary Oliver Dowden tweeted shortly after the daily press conference had finished, saying: "Dom Cummings followed the guidelines and looked after his family. End of story."

Labour has, along with the SNP and the Liberal Democrats, written to Cabinet Secretary  Mark Sedwill demanding an inquiry into what happened.

The Labour source said: "If these latest revelations are true, why on earth were Cabinet ministers sent out this afternoon to defend Dominic Cummings?

"We need an urgent investigation by the Cabinet Secretary to get to the bottom of this matter.

"It cannot be right that there is one rule for the Prime Minister's adviser and another for the British people."

Acting Lib Dem leader Ed Davey said Mr Johnson's judgment would be called into question if he did not give Mr Cummings the chop.

"If Dominic Cummings is now allowed to remain in place a moment longer, it will increasingly be the Prime Minister's judgment that is in the spotlight," said the former energy secretary.

"Surely Boris Johnson must now recognise the actions of his top adviser are an insult to the millions who have made huge personal sacrifices to stop the spread of coronavirus."

Downing Street refused to comment on the alleged developments.

In a statement issued earlier today, No 10 said Mr Cummings had acted "in line with coronavirus guidelines" when driving up to seek child support from family after social distancing measures had been put in place.