Scotland’s over-stretched contact tracing system has stopped asking positive cases about their interactions in pubs, restaurants or shops because it is "evolving", the SNP’s Health Secretary has insisted.

Humza Yousaf denied there was "a malicious reason" behind Test and Protect interviewers drastically cutting the inquiries they make of people who test positive, from 25 questions to only five, as it struggled to cope with a record surge in Covid-19 cases.

Instead, he argued the script they used was "continually evolving" and predicted the service would now improve after it fell well below a World Health Organisation (WHO) benchmark of dealing with 80 per cent of close contacts within 72 hours.

It only managed to reach 65.1 per cent of close contacts within that deadline in the week ending June 27 and 73.1 per cent the following week.

But Jackie Baillie, Scottish Labour’s health spokesman, accused  SNP ministers of "playing fast and loose with the safety of the public" and said they had "abandoned proper tracing of the virus".

The Scottish Sun on Sunday disclosed that Test and Protect interviewers are now only asking about "high risk" activities such as if people have travelled overseas, visited care homes or been in healthcare, education, food manufacturing and processing settings.

In an attempt to reduce delays caused by the spike in cases, those who test positive are no longer being asked about their close contacts in hospitality premises, shops or sports stadia.

The Scottish Government said the shortened questionnaire was based on clinical advice to use resources "proportionate to public health risks".

The change came after figures disclosed last week only 28.2 per cent of people who tested positive last week were interviewed within 24 hours by Test and Protect about their movements and close contacts.

In an effort to tackle the huge backlog, contact tracing teams have been ordered to prioritise "high risk" cases and rely on alerting more people by text message rather than calls.

Mr Yousaf announced on Friday that an extra 100 staff had been drafted in to help clear the backlog of interviews and he said on Sunday that "the daily capacity should go to approximately 5,000 cases per day in the very near future".

Pressed on BBC Scotland’s Sunday Show about the drastic reduction in questions about close contacts, the Health Secretary said: “The script is continually evolving. Right throughout the 16 months of this pandemic, that script has evolved depending on the nature of where we are in the pandemic.

“We are in a phase where the majority of the adult population is double vaccinated, for example. The questions would be different, potentially, at a time when we have the majority of the population vaccinated."

Rejecting any suggestion that the move was driven by political considerations, he added: “That is done for clinical or public health reason – it is not done for any other reason – certainly not what was being suggested.

"It’s not being done for a malicious reason.”

But a whistleblower told the Scottish Sun on Sunday: "Contact tracing is designed to stop the spread but the virus is out of control and it’s sticking plaster solutions that they’re trying to apply now.

"They’ve cut the original script back dramatically so now there’s really only five areas that the script concentrates on. I think what it does is allow them to meet this WHO target.

"But obviously, you’re not contacting lots of people in the community who have it and are spreading it in the community."

Ms Baillie said: "It is abundantly clear the SNP has abandoned proper tracing of the virus and is letting it spread unchecked.

"This is a shameful surrender and a betrayal of the efforts of staff. This SNP inaction is playing fast and loose with the safety of the public."

A Scottish Government spokesman said: "This sensible and practical approach is enabling us to focus our contact tracing efforts on the most high-risk cases and prevent further spread of the virus."