Police officers from Yorkshire and northern Lincolnshire will support colleagues in London ahead of the Queen's funeral on Monday.
North Yorkshire and Humberside Police both confirmed they would provide help to the Metropolitan Police.
Neither force would give details of the number of officers involved.
The support being provided in London as part of a huge police operation ahead of the state funeral would not affect local policing, both forces said.
North Yorkshire's Assistant Chief Constable Elliot Foskett said officers would support the Metropolitan Police to help deal with the "significant challenges" at a very "difficult and sad" time.
"We are providing both specialist and general duties police officers to work alongside other national colleagues to ensure the safety of the public visiting the capital to pay their respects," he said.
Humberside's Assistant Chief Constable David Marshall said: "I am proud that Humberside Police and our staff have been asked to support the policing operation within London and to play our part in ensuring the safety of the public at Her Majesty Queen Elizabeth II's state funeral."
Both forces said for operational reasons they could not disclose the specific number of officers involved.
However, they moved to reassure residents in North and East Yorkshire and northern Lincolnshire that local policing would not be affected by their contribution to the operations in London.
Queen Elizabeth II died at her home on the Balmoral estate in Scotland on 8 September and her state funeral is due to take place on Monday at Westminster Abbey.
The Queen is currently lying-in-state at Westminster Hall and large queues have formed along the banks of the River Thames as people wait to get a glimpse of the coffin.
The National Police Chiefs Council (NPCC), which co-ordinates mutual aid between the country's police forces, said support was being provided to the Metropolitan Police to assist with events relating to the death of the monarch.
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