The Labour Party has written to the head of the civil service calling for an “urgent investigation” into the movements of the Prime Minister’s chief adviser during the coronavirus lockdown.

In the letter to Sir Mark Sedwill, the party said that Downing Street’s explanation for Dominic Cummings’ journey from London to County Durham “raised more questions than they answer”.

Rachel Reeves, shadow chancellor of the Duchy of Lancaster, 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 letter alleged that press reports suggested Mr Cummings may have breached legal restrictions on movement, the Government’s guidance on self-isolation and official NHS advice.

Mr Cummings has insisted that he acted “reasonably and legally”.

Labour’s intervention follows SNP Westminster leader Ian Blackford calling on Sir Mark to investigate the “rule-breaking and the Tory Government’s cover-up” of Dominic Cummings’ lockdown journey to Durham.

Mr Blackford has also called for Mr Cummings to resign, stating his position as “completely untenable”.

The Labour letter laid out a number of questions that the party said had been raised by the Downing Street statement on Mr Cummings made on Saturday.

These included:

– “When was the Prime Minister first made aware that Dominic Cummings was experiencing symptoms of the coronavirus?”

– “When was the Prime Minister first made aware about Dominic Cummings decision to travel to Durham? Was this decision approved by the Prime Minister? And if so, on what grounds?”

– “Did Dominic Cummings seek advice from any part of Government, either prior to or subsequent from, his trip to Durham on either the legality of his actions or whether he was in full adherence to the rules in place during his trip to Durham?”

– “On how many occasions has Dominic Cummings travel to and from Durham since the lockdown was introduced?”

– “Does the Cabinet Office believe Dominic Cummings’s behaviour has breached official Government guidelines?”

– “Has Dominic Cummings behaviour breached the code of conduct for special advisers?”

The letter added: “I am sure you agree that senior officials and political figures play a critical role in ensuring the British public continue to have confidence in the Government’s approach to tackling the current crisis.

“By undermining this confidence, it undermines our collective effort to beat the coronavirus and the sacrifices millions of us have had to make.

“The British people do not expect there to be one rule for them and another rule for the Prime Minister’s most senior adviser.”