Union leaders say they are considering reporting Scarborough and North East Yorkshire Healthcare NHS Trust to the professional standards body for nursing.

And last night MP Greg Knight called on Health Secretary Alan Johnson to intervene.

The nurse was in sole charge of the 30-bed Kent ward at Bridlington Hospital over the bank holiday weekend last week – when under-pressure services in the resort were potentially further stretched by the influx of thousands of visitors.

The mixed general medical ward should be covered by seven nurses during the day, according to the union Unite, which said it was greatly concerned about staffing levels across the whole site.

East Yorkshire Tory MP Mr Knight called it "shocking" and demanded action to provide better patient care, saying: "This is totally unacceptable.

"To make matters worse, Bridlington is a tourist area and the population rises during the summer months and bank holidays, so this level of nursing cover is quite shocking.

"The whole problems around Bridlington Hospital are cash-related. The hospital is a relatively new building. It was built in the 1980s as a purpose-built hospital and in NHS terms is therefore a modern building. Services should be expanded, not cut back as they are."

He added: "I am pleased that Andrew Lansley, the Shadow Health Secretary, has made it quite clear he feels Bridlington Hospital has a viable future and he is opposed to what is happening there."

The cash-strapped trust, which runs the hospital, has previously been accused of deliberately running down services in Brid-lington as it pursues plans to save £2m.

It intends to shed 70 jobs, close two acute medical wards at Bridlington and transfer the hospital's six-bed cardiac monitoring unit to Scarborough.

It only shelved plans to axe 600 jobs – one-third of its workforce – last year when the Strategic Health Authority agreed to suspend the bulk of its historical debt of £12m.

The latest revelation comes just weeks after the same trust was criticised for launching a recruitment drive for finance staff while it was known to have a shortage of nurses.

Unite health spokesman Kevin Coyne said: "The nursing levels at Bridlington Hospital are critically low and we are extremely worried about the impact on the care of those on the wards.

"We are considering reporting the matter to the Nursing and Midwifery Council because we believe this is unsafe practice.

"We believe it is death by a thousand cuts because the trust is intent on closing the wards in question. Clearly the wards are understaffed at the moment and they intend moving services to Scarborough. We believe that is wrong."

Last month the trust advertised 17 finance posts with a combined annual wage bill of about £450,000. The positions range from head of finance and procurement – salary £60,669 to £75,114 – to payables clerk, worth between £12,577 and £15,523 a year. Trust chief executive Iain McInnes insisted they were necessary to secure the trust's future.

Plans to close the cardiac monitoring unit and two wards at Bridlington have been referred to Mr Johnson. A proposed change to maternity services across the trust's hospitals is being considered by the Independent Reconfiguration Panel, set up in 2003 to advise the Secretary of State on contested proposals for health service change.

The proposed shake-up at Bridlington has met with fierce local opposition. In March a petition bearing more than 37,000 signatures was handed in to Downing Street calling for the services to be retained.

The Save Bridlington Hospital Campaign Action Group, set up in 2002, is organising a protest march through the town on July 26.

Campaign chairman Mick Pilling said: "Staff shortages have been ongoing for that last 18 months and nothing has been done.

"This is mismanagement and has come about because the trust have been more concerned about balancing the books."

He said morale among nurses at the hospital was at an all-time low.

Neither the Health Secretary nor anyone at the trust was available for comment.