Ms Slater, the minister for green skills, the circular economy and biodiversity, is reported to have told civil servants and advisers that she did not want to do “any more than two things in a day” during the summit.
With the climate conference, which was staged in Glasgow, running for two weeks, Ms Slater, who missed part of the event because she was isolating after testing positive for Covid, also said she “can’t be working 14 days straight” and “needs two full days completely off”, although these “don’t need to be consecutive”.
Details of the email, which was obtained under Freedom of Information, were reported by the Scottish Sun newspaper.
Scots Tory environment spokesman, Graham Simpson, told the paper: “This astonishing email reads like the demands of a Hollywood diva, not a Scottish Government minister.”
He added: “The future of the planet was on the line, so it defies belief that an environment minister should be putting restrictions on her workload and insisting on days off during this crucial summit.
“Emissions don’t take days off. If she wants to be a Government minister, Lorna Slater must grow up and accept the responsibilities that come with the job.”
However, Ms Sturgeon insisted: “All my ministers work hard, they’re expected to work hard, and I wouldn’t have it any other way.”
She added: “Lorna is an incredibly hard worker. I’ve seen that in the time that she has been in the Scottish Government.”
Ms Sturgeon said the comment about wanting two days off was “over the course of a 14-day period”.
The First Minister, who brought the Greens into her Scottish Government after signing a cooperation agreement with the party, added: “All ministers will have different patterns of working to take account of all sorts of things but Lorna and the rest of my ministerial team are hardworking, as the country has every right to expect them to be.”
Meanwhile, Labour MSP Mercedes Villalba tweeted: “It’s not ‘making a fuss’ to ask for one day off a week. It’s not ‘lazy’ to attend two events a day alongside ministerial duties.”