A police force has been rated "inadequate" at investigating crime by inspectors who also raised concerns about its ability to keep people safe.

The latest Police Effectiveness, Efficiency and Legitimacy (PEEL) report found Gloucestershire Constabulary's performance has "deteriorated" since its last inspection.

Temporary Chief Constable Maggie Blyth said she accepts the report's findings but said they needed practical and financial help from the government to make improvements, which had been "repeatedly asked for".

Chris Nelson, Police and Crime Commissioner for Gloucestershire, said the report was not pleasant to read but "absolutely none of it is a surprise".

The PEEL report by His Majesty's Inspectorate of Constabulary and Fire & Rescue Services (HMICFRS) followed a recent inspection.

The force's overall leadership was also found to be "inadequate", while crime prevention, safeguarding children and adults, and responding to the public were rated as "requiring improvement".

In a staff survey conducted as part of the report, almost 20% of staff said they wanted to leave the force "as soon as possible".

Inspectors also found the number of offenders brought to justice was too low, no improvements had been made in its ability to protect vulnerable people, and the force did not have the "right capacity or capability" to manage fraud.

It did find that improvements had been made in the use of stop and search powers, and the force was judged as "adequate" in using its powers "fairly, appropriately and with justification".

The constabulary was also found to work well with other bodies to improve how it responds to children and adults at risk of harm, including victims of domestic abuse.

But HMICFRS inspector Kathryn Stone said she had "particular concerns about how the constabulary is managed and how well it investigates crime".

The report also recommended that in the next six months the force improves its leadership, ensures officers have the right skills to investigate crimes, and ensures investigations are consistently carried out in a "thorough" and "timely" way for victims.

Despite the findings, Blyth said she is proud of the "fantastic workforce" but added that it is "frustrating and disheartening to not be able to support them in the way we want to".

"I am proud of the improvements we have made in Gloucestershire in the past couple of years, particularly given the restraints we are working with and of the continued commitment of our people to serve the public," she said.

"But ultimately we can only do so much without more support or the modernising of policing's structures through reform." Nelson said the force has been "struggling for some time" but added the report "is not good enough".

"To be rated inadequate in investigating crime, a fundamental service of a police force, is, to say the least, disappointing and reflects a weakness seen in many police forces nationally," he said. He added that faster improvement for the constabulary is "non-negotiable".

In a statement the Home Office said it is "delivering the biggest reforms to policing in over 200 years" to allow forces to better protect communities.

A spokesperson added: "Police force funding this year is at a historic high of £18.5 billion, with Gloucestershire Constabulary receiving a cash increase of 4.7 per cent."