Dyfed and Powys did not hire any additional police officers last year, new figures show.
It comes as the headcount of police officers across England and Wales fell following the end of a recent recruitment drive which aimed to recruit 20,000 officers.
The Police Federation of England and Wales said pay and working conditions are pushing police officers to leave the force, and urged the Government to "wake up and face the truth" and provide "long-term, stable funding".
New Home Office figures show Dyfed-Powys Police did not add any officers to its ranks in the year to September, despite gaining 43 the previous year.
As of September, there were 1,318 officers in the force in Dyfed and Powys, corresponding to 252 per 100,000 people.
Nationally, the headcount of officers stood at 148,900 – down 278 from the year before and dropping from a peak of 149,800 in March.
The Government's Police Uplift Programme, which was introduced by Boris Johnson and ended in March 2023, met its target of recruiting 20,000 police officers across England and Wales.
But with officers now leaving the force, the Police Federation of England and Wales said the Government must "wake up and face the truth: people are leaving the police service for a reason".
Tiff Lynch, acting national chair of the organisation, said: "Our surveys make it crystal clear – it's the relentless erosion of fair pay, poor conditions, and the lack of support for the tough, dangerous work officers do.
"If they don't act, we'll keep losing officers. Policing needs long-term, stable funding, not the constant cycle of boom-and-bust recruitment strategies.
"Quick fixes won’t cut it. We need a sustainable solution, or the consequences for communities across the country will be tragic."
The Home Office figures also show Dyfed-Powys Police lost one full-time equivalent officer from its ranks in the year to September, while it gained 44 the year before.
Across England and Wales, the number of FTE officers fell from a record 147,700 in March to 146,900 in September.
It was the lowest figure since September 2022.
However, the total paid police workforce size (including police officers, police staff, designated officers and police community support officers) in England and Wales increased by 0.2% between March and September.
In December, the Prime Minister promised a £100 million investment in the Neighbourhood Policing Guarantee to deliver 13,000 additional neighbourhood policing officers, police community support officers and special constables by the end of this Parliament.
A Home Office spokesperson said: "As part of our mission to make our streets safer, we will restore neighbourhood policing and ensure every community has a named and contactable neighbourhood police officer.
"We will deliver an extra 13,000 neighbourhood police officers, community support officers and special constables, all of whom will play a vital role in bringing visible policing to our streets.
"Alongside this, we are committed to working with police forces to ensure overall officer numbers are protected."