THE UK Government is refusing to sack Dido Harding despite mounting pressure from Tory and opposition critics.

The NHS Test and Trace chief is under fire amid accusations the system is failing to stem the spread of coronavirus in England.

The system hit a record low last week with just 59.6% of the contacts of people who tested positive being successfully contacted and told to self-isolate.

Northern Ireland Secretary Brandon Lewis insisted that Harding was doing "a very good job" after one senior Conservative MP called for her to be replaced by a military commander.

However, Labour warned her position was "untenable" as it emerged ministers were considering cutting the time people have to self-isolate if they have been in contact with someone who has the disease because of concerns over public compliance.

At the same time it was reported that Boris Johnson has become "disillusioned" with the data he is receiving from Test and Trace after some of the figures he was given turned out to be inaccurate.

READ MORE: Tory minister denies bankers will be exempt from quarantine rules

During a round of broadcast interviews, Lewis rejected calls for Harding – a Conservative peer and former TalkTalk chief executive – to be dismissed, although he acknowledged that the service needed to improve.

"What Dido has done is put together and drive forward a team that has come on so much in the last few months," he told Sky News's Sophy Ridge on Sunday programme.

"We want to see it improve, we want to see it grow and get better and better. That's how we fight this virus. But actually I think Dido and the team have done a very good job to get to where we are."

However, in a scathing attack, senior Tory backbencher Sir Bernard Jenkin said there was a "vacuum of leadership" at the top of the organisation and that public consent and co-operation was "breaking down".

Writing in The Sunday Telegraph, he said Harding should be given a "well-earned break" so she and others could "reflect on the lessons learned so far" and that a senior military figure should be appointed in her place.

"There is a spaghetti of command and control at the top, which is incapable of coherent analysis, assessment, planning and delivery," he wrote.

"The immediate priority is to fill the vacuum of leadership in Test and Trace, which is destroying cooperation and compliance.

"Government harnessed the military to regain control in the foot and mouth crisis; the Prime Minister should follow that example today, by installing a single leader, a three or four star military commander with a reputation for handling complexity under stress."

Appearing on the Sophy Ridge on Sunday programme, Jenkin, who chairs the Liaison Committee of senior MPs which questions the Prime Minister twice a year, insisted his comments about Harding had been meant "kindly" and that she was a "tremendous asset".

However, he added: "The Test and Trace capability clearly needs to move up several gears and it's what leadership does, not who leadership is that really matters. It is the sense that there is a lack of an overall strategy which I think is at the heart of the problem."

For Labour, shadow mental health minister Rosena Allin-Khan said Lady Harding's position had become "untenable".

"The Tories are in-fighting because even they can see just how catastrophic the test, trace and isolate system has been," she told the Sophy Ridge on Sunday programme.