The UK and Scottish Governments are in the final stages of negotiations on policing for COP26 and Westminster is prepared to foot the bill, according to the acting head of the Scottish Police Authority (SPA).

Holyrood and Westminster have been engaged in a spat over who will cover security costs at the 10-day climate summit, due to be held in Glasgow in November.

The Scottish Government has insisted the UK Government should pay, although First Minister Nicola Sturgeon recently called for a “reset” in the relationship between the two administrations when it comes to dealing with the summit.

Lynn Brown, SPA acting chief executive, has said negotiations are now in their final phase for the UK Government to pick up the tab, through a mixture of funding via the Scottish Consolidated Fund, drafting in reinforcements from other forces across the country and an accommodation payment from the Foreign Office.

She told a meeting of the SPA board on Wednesday: “It hasn’t be specifically agreed but that’s highly likely to be what we’re doing through mutual aid.

“The Foreign and Commonwealth Office have also been very helpful on accommodation, they will deal with that and that takes out another significant amount of money – about £28 million to £30 million.

“We’re trying to reduce the risk [attached to] the money coming to Scotland but we’re hoping to bottom that out in the next few weeks.”

An SPA report has claimed costs could be as high as £250 million, although the figure is considered to be an estimate for the “worst-case scenario”.

The value of the reinforcements to be sent to Scotland for the duration of the summit – when world leaders are expected descend on Scotland’s largest city – would be around £113 million based on current costing estimates and discussions are currently ongoing with the Home Office.

In terms of cash sent to the Scottish Government through the Scottish Consolidated Fund – the main funding avenue at Holyrood, which receives the annual block grant from Westminster – responsibility for how the money is spent will lie with the Scottish Government and Ms Brown, who will be the accountable officer for the fund.

A total of 30,000 delegates are expected to attend the summit and climate protests could bring out an estimated 500,000 people.

Reports suggest the UK Government has scouted potential sites for a move of the summit, although a spokesman for the Prime Minister has said he is “committed” to holding the summit in Glasgow.

A spokesman for COP26 said: “Discussions on costs for COP26 are currently ongoing, and final budgets are yet to be confirmed.

“We are continuing to work closely with Police Scotland and the relevant authorities to make COP26 a secure and welcoming event that ensures value for money for the UK taxpayer.”

A Scottish Government spokeswoman said that Justice Secretary Humza Yousaf had “made clear directly to his UK counterparts the expectation that all costs arising from the decision to hold COP26 in Glasgow will be borne by the UK Government”.

The spokeswoman added: “This includes funding for police, fire and ambulance services which are essential to both prepare for and deliver a safe, secure and successful event.

“Scotland looks forward to welcoming the United Nations delegates and participants from around the world later this year. Scotland is recognised internationally for its strong track record at hosting major international events and we are working collaboratively with the UK Government, Glasgow City Council and other partners to ensure the conference is a success.”