CORNWALL'S out-of-hours GP service has failed four essential quality and safety standards, according to a damning report by regulators.
The Care Quality Commission (CQC) found Serco was not employing enough clinical staff to meet patient demand and did not have an effective system to assess the quality of its service.
Inspectors visited its Truro headquarters at Treliske and five clinics in April and May following concerns raised by staff, service users and local MPs.
The report said Serco admitted it had a shortage of doctors, underestimated demand during the Easter weekend and was unable to cover some GP shifts on the May Bank Holiday.
At the beginning of the year, it employed between 4 and 5 GPs, increasing to 12 at the time of the inspector's second visit in May.
The Cornwall and Isles of Scilly Primary Care Trust also relaxed its rules governing the use of agency doctors, allowing an increase from 20 per cent to 32 per cent as an interim measure between April and June this year.
CQC has given the provider 14 days to say how it will improve the out-of-hours GP service that half a million people depend on.
CQC's inspectors will then revisit, unannounced, to confirm improvements.
During the inspection, CQC officials spoke to current and former members of staff who asked to pass on information in confidence, many fearing potential repercussions.
Serco was meeting four of the essential standards but failed four others, including not having enough qualified, skilled and experienced staff to meet people's needs, with many doctors working double shifts.
Complaints included one patient waiting at a clinic for 90 minutes and another giving up waiting for a home visit and dialling 999.
Serco had been accused of altering targets to enhance its performance, although CQC found no evidence to prove this. It did conclude that Serco's system to fully assess and monitor the quality of its service was not effective.
It also said not all staff received appropriate training.
Ian Biggs, deputy director of CQC in the region, said: "At times, Serco has not had enough doctors on duty and it is hardly surprising that people have complained. Asking GPs and their drivers to work such long hours should be a last resort."
In a statement, Paul Forden, managing director of Serco's clinical services, said it had already taken action to ensure three of the four areas had "made progress" and achieved the required standard.
On training, he said it was 92 per cent compliant and expected to fully meet the standard within a month.
"Patient safety and wellbeing is our first priority," he added. "We have taken, and will continue to take, any criticisms extremely seriously, and we have fully co-operated with the CQC in its investigation."