The children's ward at a West Lothian hospital is closing to admissions over the summer, the third time such a measure has been imposed.

The paediatric ward at St John's Hospital in Livingston will instead operate as an "assessment and programmed investigation unit" from July 7.

NHS Lothian said a shortage of doctors able to cover the ward overnight and at weekends had forced it to make the "difficult decision" to cut inpatient services.

Children taken to St John's will still be assessed but will be transferred to the Royal Hospital for Sick Children in Edinburgh for admission.

Calls were made for the ward to remain open after staffing issues forced it to close to inpatients over the summer in 2012 and 2015.

Lothian MSP Neil Findlay said locals would be "furious" at the closure.

Last year, a report from the Royal College of Paediatrics and Child Health (RCPCH) said St John's should introduce resident consultants in hospital overnight to retain the inpatient service.

The health board has said it will reopen the inpatient services "as soon as possible" after the summer.

Jacquie Campbell, chief officer of acute services at NHS Lothian, said: "The safety of our patients must be out top priority and this is a difficult and deeply frustrating decision to have to make.

"I would again emphasise our on-going commitment to St John's Hospital and the children's ward. This has been demonstrated through the significant investment in recruitment over the years and in the work that went into the RCPCH review.

"We have relied on our dedicated staff from St John's and across Lothian to work additional hours to provide these important services. Despite our best efforts we have been unable to reliably secure the levels of staffing required overnight and at weekends to guarantee a safe service."

She continued: "If we don't make changes now to the operating hours of the children's ward, we run the risk of having to make an unplanned closure at a few hours notice, which would lead to the sudden diversion of patients. This reduction in opening hours is the safest option for the children of West Lothian.

"We are committed to reinstating the full service as soon as possible after the summer and will be working with the chief medical officer, Scottish Government and the Royal College of Paediatrics and Child Health to review the steps we have taken and to identify what else can be done to guarantee safe, sustainable staffing for this service."

NHS Lothian said parents were not being asked to do anything differently and maternity services would be unaffected.

Children who currently attend the ward will continue to be cared for as normal, the health board said.

Scottish Labour MSP Neil Findlay said the Scottish Government had broken promises to keep the ward open: "Following previous closures, the SNP claimed the safety and staffing issues at St John's would be resolved. Now yet again we are told that the ward will close to inpatients for an indefinite period over the summer.

"Local residents will rightly be furious at the downgrading of services that will leave them and their sick child having to make a 20-mile trip to Edinburgh.

"Nicola Sturgeon promised to support the retention of these services. She has clearly broken that promise."

Health secretary Shona Robison said new staff had been hired for the children's ward.

She said: "NHS Lothian has taken a number of steps to improve recruitment in this area, in line with the Royal College of Paediatricians recommendations, ‎including seeking to recruit 8 extra consultants, consultants covering shifts directly and the use of locums.

"I understand that this temporary measure is being taken in the best interest of children and their families. I have written to the board today to emphasise the importance I attach to early reinstatement of this vital service.

"NHS Lothian has assured me they will engage again with the Royal College of Paediatricians to identify solutions for sustainable services for patients."