Police officers have insisted public safety will not be compromised as they prepare to "withdraw goodwill" in a pay dispute.
The Scottish Police Federation (SPF) has begun its "most overt" action in a century.
Scottish officers are protesting about a "derisory" £565 pay rise offer.
By law, officers cannot take industrial action but will now charge for all overtime and refuse to begin shifts early.
Police Scotland said it was committed to seeking a pay settlement through the Police Negotiating Board, with talks set to resume next Monday.
Nicola Sturgeon has said she hoped police officers would agree to a "fair and affordable" deal.
The £565 pay offer made to officers was rejected by the governing body of the SPF, representing rank-and-file officers, last week.
In a letter to members on Thursday, SPF general secretary Calum Steele said he had received communication from the official side of the negotiations - which includes the Scottish Police Authority, Police Scotland and the Scottish government.
At this time there is no reason to change our position on the withdrawal of good-will. That will proceed as scheduled from 5pm tomorrow. https://t.co/hGz0JjnnXf— ScotsPolFed 🏴🇺🇦 (@ScotsPolFed) June 30, 2022
He said it would allow discussions on the pay claim to resume next Monday, but confirmed on Twitter that the withdrawal of goodwill was going ahead as planned at 17:00 on Friday.
Mr Steele said: "We are back at the negotiating table, but we do not yet have a formal improved offer.
"As a result, it's pretty important that our members are able to continue to demonstrate their frustration.
"Hopefully that will act as a reminder, during the discussions that are hopefully kicking off on Monday afternoon, of just how important an issue this is for police officers."
Mr Steele "guaranteed" public safety would not be compromised by officers' actions.
As the action kicked in on Friday, Mr Steele told BBC Scotland's The Seven programme he believed that if strike action was an available option, some officers may have chosen to walk out.
"Such has been the level of anger and disquiet given settlements and offers that have been given elsewhere and particularly because of the lack of rights that are available to police officers when it comes to trying to resolve many of these industrial disputes," he said.
He added: "The long-term aspiration of anyone that works in any trade union or any police trade union-type body, has got to be to secure the maximum possible rights for the members that they represent."
'Taken for granted'
The SPF boss had previously told members the action was not taken to "frustrate any investigation, or further aggravate any victim's experience".
"It is simply to demonstrate to our employers just how much discretionary effort, and free policing hours, they ordinarily take for granted," he added.
The initial withdrawal of goodwill involves:
- Police officers not beginning their shifts early
- Ending their shifts at the rostered time unless expressly told to work late
- If they are lawfully ordered to work additional hours, claiming payment for every period of overtime
- Officers not taking personal protective equipment home at the end of the day, regardless of where they are due to start their next shift
- Not taking police equipment such as Airwave radios home.
The general secretary said the action - the "most overt" action by members in more than 100 years - had not been endorsed by the federation lightly, but showed the "utter contempt" police had for the pay offer.
A Police Scotland spokesman said it was committed to seeking a pay settlement.
He added: "We recognise the considerable goodwill officers bring to their roles on a daily basis as they keep people safe across the country, and this is also valued by the communities they serve."
'Officers do deserve pay increase'
The leader of the Scottish Conservatives, Douglas Ross, raised the issue at First Minister's Questions on Thursday, saying the SPF had described the current pay offer as "derisory".
Ms Sturgeon said police officers were suffering from a cost of living crisis "exacerbated by the Tory government".
She said officers in Scotland were paid more than in the rest of the UK, there were more police officers per head of population in Scotland than in England, and the policing budget was due to rise by £40.5m this year.
"There is a pay negotiation under way," she added. "I would fully expect the Scottish Police Federation and any trade union and professional organisation to stand up for their members during a pay negotiation.
"I hope all sides will continue to work together constructively to ensure that a fair and affordable pay increase can be agreed for our police officers.
"Our police officers do deserve it and we will continue to value policing and give it the priority it deserves."
Mr Ross responded: "The first minister's on a different planet.
"She's saying it was a constructive meeting between her justice secretary and the federation, and the federation said this morning that their members are now taking the most overt demonstration of action in more than 100 years."