Scottish Secretary will "argue strongly" for Westminster to manage supply of Scottish antibody tests

He also suggested that Scotland may "catch up" with England in terms of lockdown measures "within a couple of days" during a sitting of the Scottish Affairs Committee this afternoon.

It comes after health experts in England said an antibody test developed by Swiss pharmaceutical firm Roche was 100% accurate, with commercial discussions now ongoing.

Indications so far have been that frontline healthcare workers would be first in line to receive the tests, although some medical experts have warned that having antibodies to the coronavirus is not yet known to make someone immune to it, or for how long.

Boris Johnson previously described such a test as a "game-changer"

At her daily briefing today, the First Minister said that the news of a viable test was " positive" but warned: " That is not the whole story because we still don't know what the implications of somebody having an antibody response to this virus is."

Nicola Sturgeon added: " Does it mean you've got immunity? And if it does mean you've got immunity, how long does that immunity last?

"We are learning all the time which is why we have to remain as flexible as possible in how we tackle this."

Manwhile, Abbott, another global healthcare company, said its Covid-19 “laboratory-based antibody test has been successfully evaluated by public health bodies for England, Scotland and Wales as ‘highly specific’ and they have communicated evaluated specificity results between 99.73% and 100%”.

It added it was now working closely with the NHS and had “commenced shipping to NHS laboratories to enable them to receive samples based on Government direction”.

The company said it has a capacity to provide five million tests to the UK each month, starting immediately.

When asked by Conservative MP Andrew Bowie MP this afternoon if he believed the "four nation approach" towards tackling the pandemic "might be extended to purchasing of such things as antibody tests so we can all get the benefit across the entire UK" Mr Jack said: "Yes, I do."

He added: "We have a centralised PPE facility in Liverpool where we have supplied millions of units of PPE to the Scottish NHS, under request.

"I would expect to have some centralised purchasing for this antibody test, it would be a very good thing and it should be fairly distributed throughout the UK. I shall be arguing for that strongly."

The Scottish secretary also suggested Scotland could "catch up" with England's lockdown measures "within a couple of days".

He said: "I still think that if we can, if we can get the R-rate to fall a bit faster in Scotland...I mean I think Scotland is only a few days behind.

"I've seen the numbers across the whole of the UK by nation and by region, I would say that within a couple of days Scotland can catch up, certainly within less than a few weeks, and we can hopefully all move forward with the same messaging and the same guidelines across the UK, because that's what keeps people on the straight and narrow when they can see consistency."

John Lamont, Conservative MP for the Borders, asked for reassurances that police would not be deployed to patrol the border and stop people coming in to Scotland from England. The suggestion had been made previously by SNP MP Angus Macneil.

Mr Jack said: "I can absolutely reassure [him] that's not going to happen.The chief constable of Police Scotland has made it clear that's not going to happen, "He's also made it clear the border is not a problem...There is no intention to put up the barricades at the border, that is not happening."

SNP and LibDem MPs also asked about communication with the Scottish Government and why Nicola Sturgeon had not been told about the change to the 'Stay at Home' message on Sunday. Pete Wishart, long-serving SNP MP, said the government had made a "pig's ear" of the message.

Mr Jack replied that it was "crystal clear" there was going to be a change to the messaging, but added: "The detail on the messaging change, the context, was left to the communications experts. Everyone knew a change was coming.

"The First Minister said she hadn't been consulted and that's correct, because the message was for the communications experts... we had to acknowledge we had to change people's perceptions. 'Stay at Home' was hugely successful...and the decision was taken that we needed to get people thinking about going back to work, it was to change the nuance and psyche of people as they move into different environments."

Mr Jack did acknowledge there had been confusion over the message, after SNP MP Mhairi Black asked why Boris Johnson had not made clear his new advice applied to England only.

He said: "It did cause some confusion.

“The broadcast on the Sunday evening, I think we’ve all accepted that could have been more specific but the UK Government was very quick to make the position clear immediately afterwards.”