The size of the NHS waiting list for elective care grew in January, bucking the pattern of previous years where the number of patients waiting reduced during the month, according to latest figures for England.

There were 2.9 million patients on the waiting list in January, according to the NHS England data for that month, published this week.

This does not include the waiting lists of three trusts – Barking, Havering and Redbridge University Hospitals, Whittington Health and Barnet and Chase Farm Hospitals – which have not reported for several months due to IT problems.

In the last six years the waiting list has decreased in January. However, the figures show this year the list increased – from 2.88 million in December to 2.90 million in January.

Waiting times expert Rob Findlay said the January rise was “unprecedented”.

Last month he predicted that, as the waiting list continues to grow, there was a “significant risk” that one of the 18 week targets would be breached for England as a whole this year. After analysing the latest data he said: “January’s unexpected rise in the number waiting has only increased the risk that 18 weeks will be breached nationally this year.”

In January providers were still managing to treat both admitted and non-admitted patients within target times. Some 90.4 per cent of patients started admitted treatment within 18 weeks in January, just above the 90 per cent standard. 96.3 per cent of non-admitted patients started treatment against the 95 per cent target.

However, in January last year performance was 92.6 per cent for admitted patients and 97.5 per cent for non-admitted, when the waiting list was smaller – at 2.5 million.

The number of patients waiting more than 52 weeks in January was much lower than at the same point last year – down from 842 to 430 in the latest figures.

An NHS England spokeswoman said: “More than a million patients are treated each month and the vast majority of patients are continuing to receive treatment within the 18-week target, with half waiting about 10 weeks or less.”

“Every area in the country should achieve the contractual operational standards for waiting times in the NHS Standard Contract. NHS England has already set out a zero tolerance approach to all over 52 weeks waiters. Performance data on waiting times will continue to be published to ensure variation is identified so that NHS England can work with clinical commissioning groups and their providers to address this.”