The government's test and track chief has failed to answer a series of questions about the scheme's progress- despite minister's hailing the new system as "world beating".

Appearing in front of the Commons Health and Select Committee Baroness Harding refused to give crucial details about the scheme.

A visibly irritated Jeremy Hunt asked Baroness Harding to write to the committee before the end of next week with answers to questions he says she was given notice of in advance of Wednesday's hearing.

He referred to the "ream of letters" they should expect from the Baroness and said that the lack of information made it difficult for the committee to scrutinise the government.

Asked how many tests are coming back within 24 hours, Baroness Harding said she could give "broad averages" that have not yet been validated, adding that more that 90% of all tests come back to people within 48 hours.

Test and trace will play a role in opening up the UK again

Mr Hunt said: "What no one wants to tell us is the overall proportion of tests that come back within 24 hours. You must know that. That just can't be right. You're saying that you don't actually know how many tests come back within 24 hours and you're in charge of NHS Test and Trace?"

Baroness Harding replied: "I have not had the data validated by the authority who has expressed concern over previous testing data not having been validated."

Asked if she will write to the committee within a week and give them the answer, she said: "I'm sorry to be boring - provided that the quality of the data is good enough."

Baroness Harding said she "fully" expects to be able to, but does not want to give "false assurance".

Baroness Harding said that the NHS Test and Trace programme would produce a weekly "dashboard" providing data on the programme both at a national and local level.

Responding to repeated complaints by the chair of the committee Jeremy Hunt that she did not have the answers to her questions, she said: "This is a service that is only six days old, and building trust in NHS Test and Trace is going to be absolutely critical.

Jeremy Hunt was unimpressed with Baroness Harding's responses

"So, we need to make sure that any data that we share is accurate and validated."

She added: "I am not going to pretend that this is perfect... but there is a lot that we are doing that will enable us all to stay safer."

Mr Hunt set out the series of questions Baroness Harding had failed to answer.

He said: "How many people are contacted within 24 hours when they've tested positive, what proportion of people?

"What proportion of people are willing to share their close contacts?

"How many of those close contacts are then contacted by the call centres within the following 24 hours?

"And what do we think the compliance rate is with self-isolation?

"So those are the four bits of data that we would like. Would you write to the committee and give us that data by the end of next week?"

Baroness Harding replied: "I'm delighted to say that I will do that with only one proviso which is that the data I send you I want to make sure that the UK Statistics Authority are happy with."

Asked about NHS Test and Trace being open to "malicious use", with people falsely saying they had contact with police officers for example, Baroness Harding told the Health Committee: "That doesn't fit with what we're seeing so far either in the public attitudes or in the responses that our contact tracers are seeing."

She said it would be "quite hard" to scam people in the way that was described, adding: "I'm not saying that it is impossible.

"And we are taking fraud really seriously at all stages in the process.

"But in the end, this is actually a whole system based on societal trust, that the way that will enable all of us to get back to living more of a normal life is that we all follow the basic rules of NHS Test and Trace, and the early evidence is that's what is happening."