The UK’s largest public sector union, UNISON, has called for urgent action to regulate private patient transport services amid fears of a lack of staff checks and training.

The calls come in the wake of a damning undercover investigation that showed shortcomings at a company employed by at least two Birmingham hospitals.

Birmingham’s Women’s Hospital has suspended a contract with a private ambulance operator after an investigation found shortfalls in staff vetting and training.

Bosses said it was halting work with Health and Community Ambulance and Patient Transport (HCAPT) immediately and would investigate allegations staff qualifications were not checked properly, members’ criminal records were not checked and some worked lengthy hours.

Birmingham Children’s Hospital, which has a contract with HCAPT, said it would continue to use the firm while it looks into the claims.

An undercover BBC reporter made the discoveries during a two-week stint with HCAPT, when he was able to join the company without criminal or licence checks.

He recorded an ambulance staff member describing how he should not have been working for the firm, which operates a non-emergency service for hospitals, because he had served 18 months in prison for threatening to kill someone.

A driver was also filmed admitting he had not had a first aid training session for three years.

A spokesman for the Women’s Hospital said: “We would like to reassure the public no trust patients have come to harm whilst they have been transported by Health and Community Ambulance and Patient Transport Service.”

A spokesman for the Children’s Hospital said its contract with HCAPT cannot be “easily revoked” but they confirmed the staff involved had been suspended.

He added:  “We want to reassure parents, children and the wider public every child being transported in an ambulance is accompanied by a healthcare professional and/or their parent or guardian. In two-and-a-half years at over 20,000 journeys per year, there have only been two minor complaints about this ambulance service.

“There would be a huge detrimental impact on children’s treatment if the contract were revoked.”

He concluded the issues were taken “very seriously” and said the hospital had taken the necessary steps to manage the contract and ensure ongoing safety, while continuing with the investigation of the ambulance company.

The hospital’s chief executive Paul O’Connor added: “As always, our children’s safety is paramount. We are continuing to deliver a first class service.”

A spokesman for HCAPT said: “As soon as we became aware of the allegations against those members of staff we have taken immediate steps.”