NICOLA Sturgeon said Scots “must stay on our guard” against coronavirus as bars and restaurants prepare to let customers back indoors.

The First Minister said it was one of the steps out of lockdown that she remained “most nervous” about due to the higher risk of the virus spreading in enclosed environments.

It comes as the latest figures show signs that the steady decline in infection levels is beginning to plateau, and a new cluster of cases was linked to a care home in Glasgow.

Investigations had been launched after 18 new cases were reported in Scotland on Friday and 19 on Sunday - the highest single day figures in around three weeks.

Ms Sturgeon said 12 of the cases on Sunday had been detected in Glasgow, with seven of those traced by routine testing in a care home. None of those who tested positive had been showing symptoms.

It comes as figures for the last four weeks show that the fall in the number of new cases is levelling off.

READ MORE: Scotland's slower exit from lockdown has had 'marginal' effect on infection numbers, says epidemiologist

Since June 15, statistics on new positive cases of Covid-19 have been available from all testing routes: NHS labs mainly dealing with hospital cases, and community incidence identified through drive-thru centres, mobile testing units, and home testing kits.

The number of cases halved initially - from 155 in the week beginning June 15 to 80 the following week. But that has slowed in the past two weeks, with 60 new cases in the week beginning June 29 - when a cross-border outbreak resulted in 12 infections among Dumfries and Galloway residents - and 63 last week.

Asked about the recent spike in daily cases, Ms Sturgeon said there was no evidence as yet that coronavirus was on the rise, but stressed “we must stay on our guard”.

“At the moment I don’t think the public should be alarmed. When there is what appears to be a spike in cases - and remember, 18 on Friday and 19 on Sunday, these are still very low numbers but higher than they have been more generally for the last couple of weeks - when that happens we explore these very thoroughly.

“Based on the investigations thus far, there are explanations. They don’t point at this stage to a concern about accelerating community transmission. But we’re not complacent about that.

“I don’t want to see anything about this virus as inevitable in terms of increasing transmission but, as I say every day, that is down to us. It will spread again if we give it a chance.”

Indoor shopping centres re-opened yesterday, with hairdressers, pubs and restaurants set to resume trading from Wednesday for the first time since mid-March.

It follows reports that some beer gardens have been failing to take customers’ contact details as required under Test and Protect rules in case the venue is subsequently linked to a positive case.

“It’s one of the steps that I’m most nervous about because we know the risks of indoor transmission are much higher than outdoor transmission,” said Ms Sturgeon.

“But we can’t keep everything in lockdown forever. We have to get the country back to something that’s closer to normality.

“But if people or businesses don’t comply with these rules we’ll be back where we started quicker than any of us care to consider.

“A few weeks ago [Melbourne] had levels of infection lower than Scotland. It’s now dealing again with a serious outbreak and it’s back in a form of lockdown.”

READ MORE: Why some scientists now think hand-washing and distancing might be 'insufficient' against virus 

On Sunday, the World Health Organisation reported that the number of new Covid-19 cases had jumped by more than 230,000 - the biggest single daily global increase since the pandemic began.

It included a record US daily surge of 15,000 new cases in Florida, where anti-mask protests have taken place and the Disney World resort in Orlando opened to visitors on Saturday.

“Scotland is doing very well, but we must not be complacent," said Professor Jason Leitch, Scotland's national clinical director.

"There’s no suggestion that there is a localised community outbreak in any of the numbers we’ve seen over the past few days, but we’re very vigilant and we need you to follow the guidance to allow us to keep those numbers low.”

Six new cases of the virus were reported in Scotland yesterday, but there were no deaths for the fifth day in a row - though some National Records of Scotland offices are no longer open at weekends.

READ MORE: Claims 80% of population will be infected by virus dismissed as 'not a realistic estimate' by expert

Professor Hugh Pennington, emeritus professor of bacteriology at Aberdeen University, said it was "not at all surprising" that the fall in virus cases had slowed.

“What we learned from China many months ago is still the same: they got the numbers down quite quickly with their lockdown and travel restrictions, but it hung around for a long time, sort of trickling along, which is basically what’s happening now here.

"It’s probably causing family-type outbreaks, but many of these small ones fizzle out."

He said international evidence had not linked indoor malls to significant outbreaks, but said pubs and gyms would "be tricky"for infection control.

"Internationally we’ve seen outbreaks in gyms because people are in an enclosed environment and heavy breathing, and there’s been outbreaks linked to pubs.

"One of the biggest outbreaks in New Zealand was in a pub. There were more than 70 cases from one evening.

"So clearly there’s going to be an issue about some of these places releasing from lockdown because the virus isn’t down to zero - it’s still dotting about, ready to take off if it gets into one of these environments.”

However, Prof Pennington, one of Scotland's leading infection experts, said the biggest risk to Scotland now would be cases imported through air travel.

“That’s how the thing got started in the first place, we had more than 100 importations from European countries like Italy and Spain whose outbreaks started earlier.

"That's how it got going in Scotland, not from people coming from China as we'd thought.

"In New Zealand, they had a very strict lockdown which succeeded in getting rid of the virus completely, but now they’re facing the problem of people bringing it in.

"But I’m reasonably optimistic that if we we keep going with social distancing, delay certain things until virus numbers are virtually zero, and keep up with contact tracing so that we can jump on an outbreak if it occurs, my expectation is that we’ll have seen the virus off by Christmas. And if we haven’t, we’ve done something wrong.”