The Scottish government should have been better prepared for coronavirus outbreaks at universities, opposition parties have claimed.
Hundreds of students have tested positive since universities returned earlier this month.
Opposition leaders accused First Minister Nicola Sturgeon of a "basic failure" to anticipate the problem and provide more testing.
Ms Sturgeon insisted the country's testing system was working well.
And she said the rising number of coronavirus cases underlined why tough new restrictions were introduced on Tuesday to "get the virus back under control".
A further 465 positive tests were reported across Scotland on Thursday, representing 7.9% of people newly tested.
The figures are in part driven by outbreaks at a number of universities, where many students in halls of residences in Glasgow, Dundee, Aberdeen and Edinburgh have been told to self-isolate.
A total of 172 Glasgow University students have so far tested positive, with 600 in isolation, while all 500 residents at the Parker House halls in Dundee have been told to quarantine.
And 120 cases of coronavirus have been identified in an outbreak at Edinburgh Napier University.
St Andrews University asked students to observe a "voluntary lockdown" over the weekend, with concerns about the virus spreading among students arriving for the new term.
There has also been confusion about whether students in university accommodation are able to go back to their family home - with the Scottish government initially saying they could not.
National clinical director Prof Jason Leitch subsequently said students could go home for the weekend so long as they are not self-isolating and do not have Covid symptoms.
But he has since said they cannot return home because they are now in separate households from their family.
Was asked last night whether students in halls and flats can go back to parents’ homes. To clarify, they are a separate household. There are exceptions, eg caring responsibilities, but the law is clear: they can’t meet indoors with another household – even mum and dad. Sorry.— Jason Leitch (@jasonleitch) September 24, 2020
Ms Sturgeon was repeatedly challenged about the situation during her weekly question session at Holyrood, where she said "some further measures" would be introduced later.
She said the number of positive cases at universities was likely to increase, but said this underlined that the test and protect system "is working, and we must continue to have confidence in that".
The first minister also said more walk-in testing centres will opening near some universities in the coming days in addition to the two that are already open in Glasgow and St Andrews.
Centres in Aberdeen and Edinburgh are due to open from Friday, with similar facilities also planned for , Dundee, Stirling and a second in Glasgow.
Scottish Labour leader Richard Leonard said the spread of the virus at universities should have been predicted - and said there had been similar failures to anticipate a spike in demand for testing when schools returned in August.
He said the Scottish government had failed since "day one" of the pandemic to plan ahead, adding: "This failure to test is a failure to contain the virus. This will cost people their health, their hopes and possibly their lives."
Mr Leonard also said action was needed to ensure students would not potentially have to spend Christmas away from their families.
Ms Sturgeon replied that rising case numbers proved that students were being tested, adding: "It's really important we say to people that if you need tested, get tested - the capacity is there.
"The worst thing any of us could do right now would be to unfairly and unjustifiably undermine confidence in test and protect - that confidence, right now, is justified."
Scottish Conservative group leader Ruth Davidson said there was a "clear concern" that the virus could spread from university campuses when students return home, asking if the government would consider routine testing - similar to the system employed in care homes.
She said: "There is still time to get on top of these outbreaks before they spread more widely."
Ms Sturgeon said she would consider such a move, but said "routine testing is not some kind of pass out of all the other obligations" and created a "real risk of false assurance coming from negative tests".
The point about preparation was also raised by Scottish Green co-leader Patrick Harvie, who said the situation with students was "playing a significant role in relighting the fires of the pandemic here in Scotland".
He said: "The truth is that outbreaks like this should have been expected, and support and testing sites should have been in place before term started."
Scottish Lib Dem leader Willie Rennie said routine testing would be "an extra safety measure that would protect us all", saying there was a risk of asymptomatic carriers "unknowingly spreading the disease".
Ms Sturgeon replied: "Testing is vital here, but it is absolutely wrong to say it somehow an absence or shortage of testing available that is an issue with the outbreaks in student accommodation.
"If we weren't testing them, we wouldn't have seen these increases.
"We have to be careful that a negative test doesn't lead a student to say 'I'm fine, I don't need to bother with isolation or social distancing and abiding by all the rules'."