Statistics from NHS Digital reveal that between 1 July to 30 September there were 3,615 vacancies advertised for nursing and midwifery posts in the East of England.
This is up from 3,496 in the period 1 April to 30 June 2017.
Separate figures also published by NHS Digital show 349 nursing and midwifery staff were appointed between 1 April and 30 June 2017.
The RCN is concerned about large numbers of nursing posts remaining unfilled and the impact this has on staff morale and patient safety.
The figures come after reports last week revealed a large number of nurses leaving the NHS, prompting concern about the future of the workforce in the face of growing patient demand.
Across England, 34,260 vacant NHS nurse and midwifery posts were advertised in July to September last year – an increase of 2,400 on the previous quarter.
Teresa Budrey, RCN Eastern Regional Director, said: “These figures give us great cause for concern as they are further proof that the NHS is desperately short of nurses.
“It is no wonder that hospitals are buckling under the strain caused by winter pressures given that the NHS is struggling to fill these vital nursing posts.
“Years of pay restraint have had a devastating impact on nurse morale and the ability of the NHS to recruit and retain nursing staff. In turn, this impacts on patient safety.
“The Government must act quickly by investing in its nursing staff – one of the health service’s most valuable assets – and recognising the vital job they do.”
Janet Davies, Chief Executive and General Secretary of the RCN, said: “When the Government allows nursing on the cheap, patients can pay the highest price.
“It is time to draw a line under this false economy with urgent investment in services and those who provide them – including a pay rise above inflation – and legislation to make ministers accountable for workforce planning and safe staffing levels.”