Labour has called for an urgent inquiry into the Prime Minister's chief aide going on a 260-mile trip during lockdown.
Shadow minister for the Cabinet Office Rachel Reeves demanded reassurances that Dominic Cummings had followed the Government's lockdown laws.
It comes after the Mirror and the Guardian revealed that Mr Cummings had travelled from London to Durham to visit his family during the lockdown.
Boris Johnson has come under pressure to sack his closest adviser, although Downing Street has insisted Mr Cummings thought he had 'behaved reasonably and legally'.
In a letter to Cabinet Secretary Mark Sedwill, Mrs Reeves wrote: "The British people have made important and painful sacrifices to support the national effort, including being away from family in times of need.
"It is therefore vital that the Government can reassure the public that its most senior figures have been adhering to the same rules as everyone else.
"The British people do not expect there to be one rule for them and another rule for the Prime Minister’s most senior adviser."
It added that the Government's response to the story had 'raised more questions than they answer'.
A Downing Street spokesman said Mr Cummings travelled to his parents' home because his wife had suspected coronavirus and he thought he would become ill.
No10 argued it was therefore essential for him to organise childcare, with his sister and nieces offering to help.
The spokesman added: "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."
