Lifting lockdown rules to allow families to mix over Christmas will lead to a "third wave" of coronavirus in Scotland, Nicola Sturgeon has been warned.
Public health experts and MSPs raised fears about the impact of the relaxed plan, which the First Minister already admits has split public opinion.
Sturgeon also repeated confirmation a risk assessment of the new rules has not been carried out.
Today, the SNP government leader heard more concerns that the rules could be confusing and lead to a January lockdown.
Professor Devi Sridhar, an adviser to Sturgeon, said Scots will "pay" for the UK-wide relaxing of rules.
Andrew Hayward, a member of the UK Government's Scientific Advisory Group for Emergencies, known as Sage, said it will "definitely lead to increased transmission" and a third wave.
The Scottish Government agreed a four-nations approach and published rules for Scotland today but Sturgeon has publicly appealed for Scots not to take full advantage.
The rules allow up to eight people, excluding under-12s, to meet from three households indoors between December 23 and 27.
At First Minister's Questions in Holyrood today, Scottish Green Party leader Patrick Harvie raised the public health experts' views.
He said: "There were difficult judgements to make about relaxing the covid rules over the holidays especially after public expectations had been built up but within a day of announcing the rules, the First Minister was appealing to the public not to use them. It’s a confusing message.
"Let's look at what the public health experts are saying - Professor Andrew Hayward, a member of Sage, has said it’s likely to lead to a third wave of infection with hospitals being overrun and more unnecessary deaths."
Harvie continued: "Professor Devi Sridhar said we're going to pay for the Christmas holidays with probably a January national lockdown.
"This morning at the Covid committee the national clinical director confirmed that no risk assessment has been made of the impact this relaxation will have. This seems hugely irresponsible."
Sturgeon said the government "agonised" over the rules.
"We've not modelled this particular arrangement, we're looking at if and how it is possible to do that. There are difficulties in trying to model an arrangement particularly where you’re trying to persuade people only to use flexibilities where necessary," she said.
"If you want me to talk about risks, I'll be very open with people that this does carry risks."
Earlier, the first Minister said: "We know that some people will come to the view that the right thing for them at Christmas is spending time indoors with friends and loved ones, who might otherwise be isolated and alone, so we want to make sure there is clear guidance about boundaries in place.
"But we also know the virus will not take a break over Christmas and having indoor gatherings present a high risk of transmission.
"Having people from different generations in particular can be risky. Younger people often have to go out to work and can live in shared accommodation and are more likely to have been exposed to the virus."
