The policing operation for Donald Trump’s UK visit cost an estimated £18m, it has emerged.

Most forces had to cancel officers’ rest days and extend the length of shifts as the US president’s four-day trip prompted tens of thousands of protesters to take to the streets.

Sara Thornton, the chair of the National Police Chiefs’ Council, said Trump visited four force areas but there were protests in many others.

“Nearly every force supported the operation, with nearly 10,000 officers deployed from all over the country, performing over 26,000 shifts,” she said. “The full cost of the operation is still being worked out but an early estimate is nearly £18m.”

Thornton said the coincidence of the visit with the World Cup, hot weather, numerous events and festivals led to high demand on officers across the country.

Among the large protests against Trump’s visit were those held in London, Manchester, Glasgow and Belfast. The organisers of two marches that converged in Trafalgar Square, in the capital, estimated the number of protesters at more than 100,000.

However, the US president gave the demonstrations a wide berth. He attended a gala dinner at Blenheim Palace in Oxfordshire, held talks with Theresa May at her Chequers country retreat in Buckinghamshire, and met the Queen at Windsor Castle before heading to Scotland for a weekend of golf.

Summarising the latest Chief Constables’ Council meeting, which was held in Cardiff this week, Thornton said a large part of the agenda was dominated by financial issues.

“The Treasury announcement a few weeks ago about changes to employee pension contributions means that forces in England and Wales may need to find an extra £417m by 2020-21,” she said. “This is equivalent to nearly 10,000 officers, and grave concern was expressed about further reducing the sustainability of local police forces.”