It is “inevitable” that a major climate conference being held in Glasgow later this year will cause disruption to day-to-day policing, a review has warned.

An assurance review by HM Inspectorate of Constabulary in Scotland (HMICS) found policing plans are “progressing well” for Cop26, which will take place in the city from October 31 to November 12 after being delayed from last year due to the coronavirus pandemic.

Nearly 120 heads of state are expected to attend along with around 20,000 accredited delegates, meaning officers from forces across the UK will gather to help police the area.

HMICS said: “Given the complexity and challenge of policing Cop26, the size and scale of the event which will put exceptional demand on resources, HMICS believed it to be inevitable there will be an element of disruption in day-to-day policing.”

Its report said “where there is policy of non-attendance to calls of a certain nature or geographical area as a result of Cop26, this would be a policy decision and would require community communications” – suggesting some routine day-to-day calls will not be answered.

Gill Imery, Chief Inspector of Constabulary in Scotland, said: “This will be the biggest and most complex event staged in Scotland.

“It will place significant demands across policing and necessitate the largest mass mobilisation of police officers that has taken place in the UK in many years.

“As climate change is a high profile issue and as world leaders are due to attend, it will attract global political, public and media interest.

“Following our review, I am confident the leadership of Police Scotland, its officers and staff are committed to the effective and efficient policing of the event whilst maintaining delivery of business as usual and monitoring and supporting staff wellbeing.

“Covid-19 proved to be an unexpected challenge for those involved in policing and preparing for Cop26.

“Although the conference was delayed for a year, it did not necessarily mean there was more preparation time as many resources and personnel were diverted to support policing of the pandemic.

“An important observation from this review is the professional commitment by officers and staff who continued to deliver policing of the pandemic and planning for Cop26 against a backdrop of compliance with public health guidelines and lockdown restrictions.

“We also witnessed some examples of good practice which can be shared with other forces throughout the UK.”

The review offered only one recommendation: “Police Scotland and the Scottish Police Authority (SPA) should put in place measures to monitor progress against the areas for development outlined in this assurance review ensuring regular reporting of progress at SPA meetings.”

Deputy Chief Constable Will Kerr told the PA news agency: “The report was in the main very, very positive.

“It said that in terms of the welfare of the officers, in terms of operational planning, in terms of a range of other things you would expect, in terms of police in preparation for an event at a scale, I see that as really positive.

“It gives that assurance to our formal accountability that the things that they’ve identified are things that you would expect a number of months out from a massive operation of the scale that we’re still working our way through.

“So we welcome the report – it’s really helpful to have an external body come and look at what we’re doing and give us that sense of we’re in the right place at the right time in terms of our planning assumptions and planning preparations.

“But overall the report was incredibly positive and said that we’re in the right place and our planning is spot on.”