Police chiefs in Strathclyde are “stressed and strained” due to serious problems finding recruits for their ranks, the Evening Times can reveal.

Chief Constable Steve House has warned that he and the force’s most senior officers are overworked after failing to fill two key vacancies.

Mr House and his ruling board, Strathclyde Police Authority, have been forced to readvertise two assistant chief constable positions after just one candidate emerged.

The chief constable and Stephen Curran, the police authority’s convener, wrote to Kenny MacAskill, the Justice Secretary, earlier this summer to warn of the effect the recruitment crisis was having on them.

In their letter they said: “The signs of stress and strain on the senior officers are clear to us and, with the current workload, we do not feel this solution is sustainable.”

In theory, Strathclyde has a chief, a deputy and four assistants. But, since the retiral of Assistant Chief Constable John Neilson in the spring, the force has been operating with just two ACCs, both new to the rank and the city.

The letter continued: “We consider four ACCs to be the minimum level to operate an organisation of this size and complexity.”

The recruitment crisis has prompted niggles between the force and the Scottish Government.

Officials in Edinburgh instructed Strathclyde to stop the recruitment process for Mr Neilson’s replacement when only one candidate emerged.

The applicant, Chief Superintendent Campbell Corrigan had his interview for the post cancelled with just two day’s notice.

Mr Corrigan, a respected detective who led the investigation in to the Glasgow Airport bombing, is now acting in the position.

Members of the police authority believe this may have amounted to an interference in recruitment from the Scottish Government, which only has powers to approve or disapprove appointments.

Christopher Mason, a Glasgow Liberal Democrat and veteran police board member, said: “I think the officials exceeded their authority.”

The board is now seeking clarification on what powers Holyrood has over appointments. Force insiders, meanwhile, said they expected the positions to be filled by the end of September.

Strathclyde’s problems emerged as Scotland’s operational leaders called for a jobs freeze for the most senior positions. The Association of Scottish Police Superintendents said chiefs and their deputies and assistants should “share the pain” of cuts.

Strathclyde covers half of Scotland and has six chief officers. The other seven forces account for the rest of the country but have 23 between them.

A spokeswoman for the Scottish Government, said: “The appointment of chief officers is a matter for individual police boards, working with Scottish Government.

“We continue to work effectively with individual boards on such appointments.”