Scotland's education secretary, John Swinney, said this morning that reopening schools too early could undermine efforts to prevent the spread of Covid-19.
Mr Swinney also said that no decision had been taken on the reopening of schools, but reiterated the government's previous advice that they would be unlikely to open before the summer.
On BBC Radio Scotland this morning, he was asked if he could confirm that schools would not be back until after the summer.
He replied: "We said that schools will be closed for the foreseeable future, and when we closed the schools in March we said it was unlikely that schools would be back before the summer break."
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He said that first minister Nicola Sturgeon, in a publication due out later this week, would "map out some of the difficult issues that we've got to confront about how we move out of the lockdown period".
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Mr Swinney added that the government had "taken no decisions to reopen schools".
When asked about the criteria the government would weigh up, he said: "Fundamentally, this relates to the public health advice. We have to make sure that the spread of coronavirus is suppressed.
"We are seeing the progress that is being made on slowing up the coronavirus just now, but that's on the basis that only one in every 200 children are in schools today."
He added: "Now, the minute we say more young people can be in that school, we are acknowledging that the risk of the spread of coronavirus rises, and we can't afford to take that risk."
When asked if there might be a phased approach to reopening, with certain year groups attending on certain days, Mr Swinney said there were "various options that can be considered".
But he added that, given "all the sacrifices that everyone has made in the country up until now, to try to preserve life and to safeguard our National Health Service, we cannot risk undermining that good work that's been undertaken by taking too early a decision to return to normal school days".