The NHS has missed its target for starting patient treatment within 18 weeks of admission for the second consecutive month, the latest official figures show.

Performance against the target, which demands that 90 per cent of admitted patients begin treatment within 18 weeks, has also dipped slightly- from 89.9 per cent in February to 89.4 per cent in March.

The last time peformance fell below the 90 per cent red line was in 2011.

A slight growth in the waiting list for elective care from 2.89 million to 2.91 million was also reported but is likely to underestimate its true size as seven trusts failed to report waiting time data in March.

Performance on the two other targets – non-admitted and incomplete - remained broadly stable with non-admitted at 96.3 per cent and a figure of 93.7 per cent recorded for ‘incomplete pathway’ patients.

Rupert Wainwright, director of healthcare consultancy Zenon Consulting and former director of operations at Southend University Hospital Foundation Trust, said that pressures on accident and emergency departments were having a knock-on effect for elective performance.

“The biggest thing of all has been winter pressures - the sheer amount of cancellations that happen even now, week in week out,” he added.

“Surgeons are in place, theatres in place, anaesthetists in place and the patients all have to be cancelled because there are no beds to put them in afterwards because A&E pressures mean that surgical wards are full of medical patients,” Mr Wainwright said.

“In years past there would have been spare beds around but obviously with the ongoing cuts the first thing you do is you reduce the number of beds available across the system to the ones you absolutely need.

“So what that comes down to is you can get day cases through, cancer and urgents but routine cases get cancelled week in week out.”

The trusts which failed to report data in March were: Walsall Healthcare Trust; Ipswich Hospital Trust; Tameside Hospital Foundation Trust; Derby Hospitals Foundation Trust; Whittington Hospital Trust; Barking, Havering and Redbridge University Hospitals Trust; Barnet and Chase Farm Hospitals Trust.

Derby Hospitals, Ipswich, Barking, Whittington and Walsall all said they had recently moved to a new electronic patient record system, creating a delay in validating the data.

Waiting times expert Rob Findlay said: “Seven trusts are now failing to submit complete sets of waiting times statistics, and this is having a significant effect on the national data.

“There is usually a perfectly reasonable explanation when a trust does not report data (e.g. massive IT or recording failures), but with nearly 5 per cent of the waiting list now missing it is surely time for NHS England to explain why.”

NHS England chief operating officer, Dr Barbara Hakin, said: “NHS England firmly believes it is essential to have accurate information provided in a timely way to ensure better care for patients. All parts of the NHS have a role to play in ensuring data is collected and recorded accurately including trusts, auditors regulators as well as those who oversee the commissioning of care including Clinical Commissioning Groups and NHS England.”

She added: “The NHS is treating more patients than ever and the vast majority are treated within 18 weeks from referral by their GP.

“More than half are treated within nine weeks. We will be working hard with frontline staff over the summer months to treat even more patients.”