The number of coronavirus cases linked to an outbreak in Aberdeen which led to lockdown restrictions being reintroduced in the city has risen by 25 in the past day, Nicola Sturgeon has said.

The First Minister said 79 confirmed cases have now been identified and a further 30 are under investigation as being potentially connected to the 32 venues announced by the Scottish Government as possibly linked to the outbreak.

A total of 233 contacts have been traced, and Ms Sturgeon warned she expects a further rise in infection numbers on Friday.

More than half of the 67 new cases across Scotland in the past 24 hours were in the Grampian health board area, at 39, Ms Sturgeon told the Scottish Government’s regular coronavirus briefing.

She added that 17 new cases in Greater Glasgow and Clyde are being examined to see if there are any visible patterns.

The new cases take the Scottish total to 18,847 and mark the highest single day rise for more than two months.

But Ms Sturgeon said there have now been no deaths reported of people who tested positive for the virus for three weeks, with the total remaining at 2,491.

The Aberdeen outbreak was first revealed on Sunday, linked to the Hawthorn Bar on Holburn Street, with a list of other pubs and bars potentially involved published on Wednesday.

New lockdown measures came into force at 5pm on Wednesday, forcing all pubs, bars and restaurants in the Aberdeen City Council area to again close their doors.

There are just too many uncertainties about this outbreak right now so we are not yet confident that we can keep it under control without these additional measures

The First Minister said: “If you have been to any of these premises, even if Test and Protect hasn’t been in touch with you, we’re still asking you to be extra vigilant for symptoms.”

Further restrictions mean residents cannot visit each other’s homes – outside of extended household groups – and they cannot travel further than five miles for leisure.

Ms Sturgeon said people in the city council area should not go on holiday and people outside the area should not travel there – including people who live in Aberdeenshire, except those who need to travel for work.

The First Minister told the briefing that there was consideration being given to extending some of the lockdown measures to Aberdeenshire.

She said: “We are very, very mindful of the close integral links between Aberdeen and Aberdeenshire, and therefore we are looking carefully at whether there is at any stage a case that can be made for extending the restrictions that currently apply in Aberdeen city to areas within Aberdeenshire.”

She also urged people contacted by the Test and Protect teams, in Aberdeen or anywhere else in Scotland, to comply with the advice they are given.

Interim chief medical officer Dr Gregor Smith told the briefing that Test and Protect teams in Aberdeen had established links between those who were infected with the virus and foreign travel, although he said it is not clear if this contributed to their catching the virus.

He added: “Just because you’ve had foreign travel doesn’t mean to say that this is where you contracted the infection. We’ll only know the sources of each of these cases in the fullness of time.”

Ms Sturgeon concluded by thanking the people of Aberdeen for their co-operation, adding: “I know that this is a real blow to the city and all of us regret that we’ve had to take this position, but I do believe that people understand why it is necessary.

“There are just too many uncertainties about this outbreak right now so we are not yet confident that we can keep it under control without these additional measures.”

The First Minister also defended the contact-tracing process, following reports that some premises mentioned in the list of bars and restaurants had not been contacted by health officials.

She said the Test and Protect team would make judgments on who needed to be contacted based in individual cases, saying: “I would ask people to be understanding of the complex, fast-moving nature of the situations that local public health teams are dealing with.”

Ms Sturgeon said the reproduction rate of the virus has risen to between 0.6 and one, compared to the most recent estimate of between 0.6 and 0.9.

However, she said that as the number of cases drop, the reproduction number becomes less reliable.

As of last week, some 275 people in Scotland were infectious, she added.

On Thursday, 270 people were in hospital with confirmed Covid-19, the First Minister said, up by three in 24 hours. Of these, four were in intensive care – an increase of one.

A Scottish Government spokeswoman said: “As of today, 233 close contacts have been identified, although we expect that number to rise over the course of today.

“All 233 contacts have been successfully traced and contact tracers are currently working through further contacts newly identified today.

“NHS Grampian have their own in-house contact tracing staff, and are rapidly training more in order to support with the increased demand.

“An additional 16 staff and other support is being provided from the National Contact Tracing Centre and given the rising number of cases, work is under way with respect to Board to Board mutual aid as we would expect.

“As we move towards containment of the virus, it is important we remain flexible in our deployment of contact tracers and we will support boards with additional resource as and when they need it.

“Two mobile testing units have now been deployed to Aberdeen at the P&J Live venue.

“A further four mobile testing units are available to be deployed giving a total potential testing capacity of 2,000 tests per day.”