Sturgeon: Shutting down Parliament is dictatorship
The First Minister was speaking as the Queen formally accepted a request to suspend Parliament.
Shutting down Parliament to force through a no-deal Brexit amounts to "dictatorship", Nicola Sturgeon has said.
The First Minister described the move by the UK Government to suspend Parliament for five weeks, which has now been formally approved by the Queen, as "outrageous" and "an abuse of process".
Sturgeon said if the extended suspension of Parliament - also known as prorogation - could not be reversed, then "today will go down in history as the day any semblance of UK democracy died".
Her remarks come amid legal and legislative bids to halt the announcement by Boris Johnson earlier on Wednesday, with a group of MPs launching an action against it in the Court of Session.
The Prime Minister will temporarily close down the Commons from the second week of September until October 14 when there will be a Queen's Speech to open a new session of parliament.
The Queen approved the order on Wednesday afternoon to prorogue Parliament no earlier than September 9 and no later than September 12, until October 14.
Commons leader Jacob Rees-Mogg, Lords leader Baroness Evans and chief whip Mark Spencer were sent to Balmoral for a Privy Council meeting with the Queen to agree the timetable.
Johnson has said it is "completely untrue" the prorogation of Parliament is because of Brexit, and he claimed there will be "ample time" for MPs to debate the issue.
He said the new timetable would allow him to bring forward legislation for a new Withdrawal Agreement if a deal can be done with Brussels around the time of the European Council summit on October 17.
But opposition leaders have written to the Queen in protest and Commons Speaker John Bercow said the move was a "constitutional outrage" designed to stop Parliament debating Brexit.
Echoing the Speaker's comments, the First Minister accused Johnson of having "no respect for constitutional norms".
She said: "We should be really blunt and frank about this: trying to shut down Parliament in order to force through a no-deal Brexit that everybody knows will do real and lasting damage to people the length and breadth of the UK is not democracy, it's dictatorship.
"If MPs don't find a way of coming together next week to stop Boris Johnson in his tracks, then today will go down in history as the day any semblance of UK democracy died."
'This is a constitutional and political crisis. It's clear that Boris Johnson has no respect for constitutional norms.'Nicola Sturgeon
Sturgeon continued: "This is an abuse of process. Whatever Boris Johnson says and however he tries to dress it up, this is about trying to stop a majority in Parliament coming together to avoid a no-deal Brexit.
"That's the kind of behaviour you expect to see in countries that are not democratic, that are ruled by dictators, and that's happening here in the UK.
"Boris Johnson, let's not forget, is not elected by anybody other than the Conservative party, and here he is trying to shut down Parliament.
"Brexit was meant to be, supposedly, about bringing control back to the House of Commons.
"Now, we've supposedly got to accept that it's so important to force it through in the worst possible way that Parliament has to be shut down - it's completely outrageous."
On the timing of the prorogation, the First Minister said it would only give MPs two weeks to prevent no-deal before the Brexit deadline of October 31.
But she added: "I do think there is a narrow window of opportunity next week for MPs to try to do something to stop him in his tracks.
"Cross-party MPs came together yesterday to agree a plan, they have to put that plan into practice next week but, frankly, all options have to be under consideration.
"This is a constitutional and political crisis. It's clear that Boris Johnson has no respect for constitutional norms.
"I've spent my entire life being told the House of Commons is the 'mother of parliaments', that Parliament is sovereign.
"There's never been a more important time for the House of Commons to demonstrate that and if it doesn't then any semblance of parliamentary democracy in the UK is over."
Opposition leaders led by Labour leader Jeremy Corbyn agreed at a meeting on Tuesday to work together on a new law to stop no-deal when Parliament returns on September 3.
Corbyn accused the Prime Minister of a "smash-and-grab on our democracy in order to force through a no-deal exit from the European Union".
He said: "When Parliament does meet - on his timetable very briefly next week - the first thing we will do is to try and legislate and to prevent what he is doing.
"And secondly to challenge him in a motion of confidence at some point."
The Commons was expected to sit in the first two weeks of September and then break for the conference recess.
However, MPs had been planning a vote against leaving Westminster for the autumn party gatherings in late September and early October to allow more time to consider Brexit.