Singleton Hospital is currently managed by Swansea NHS Trust

Both Swansea and Bro Morgannwg trusts said a report on merger called Aiming Higher showed "a huge raft of benefits" that may mean better care for 600,000.

Meanwhile, the union Unison has raised concerns about 86 bed closures and possible Swansea job losses.

But the trust said closures would not affect the number of patients treated, and no staff would lose their job.

Last month hospital chiefs announced the bed closures would take place over a seven-month period.

No-one is going to lose their jobs and there are no plans for redundancies Calum Campbell, acting chief executive

In a letter to the Swansea trust's acting chief executive, Unison regional organiser Jeff Baker said the union believed financial cuts were behind the move, rather than improvements in health care.

Calling for a halt to the closures pending public consultation, Mr Baker said there was concern for staff welfare and jobs, as well as the effect on health services.

Acting chief executive Calum Campbell replied that the changes to bed numbers were the result of staff putting into place more efficient and effective practices.

Mr Campbell said as there was not a "significant change in service provision" he did not believe the changes required a public consultation.

POSSIBLE BENEFITS OF MERGER: Modernising and improving services would be made easier One trust covering 600,000 people would sustain existing services and support development of highly specialist services Removal of "artificial boundaries" would offer seamless access to care for patients Merging staff to create a 16,000 workforce would offer a bigger pool of expertise "Wasteful" duplication avoided Source: Aiming Higher

On a separate matter, Mr Baker claimed there could be 1,000 possible future job losses, referring to a financial document within the trust's draft interim strategy.

'Convincing arguments'

But Mr Campbell said: "No-one is going to lose their jobs and there are no plans for redundancies.

"We are, however, considering trimming our workforce of around 8,000 whole-time equivalent members of staff - by 742 by (the year) 2010.

"This would be achieved through natural wastage," he added.

Mr Baker said: "By anybody's measure that's a concern, because there are 700 less staff, 700 less jobs in the economy, 700 people out of work in the area."

Meanwhile, Swansea and Bro Morgannwg trusts revealed that the working name of the single merged body would be the Abertawe and Bro Morgannwg NHS Trust.

If the case for merger is approved by both boards on Tuesday, Health Minister Edwina Hart will be asked for her approval to begin a consultation.

Paul Williams, chief executive of Bro Morgannwg NHS Trust, said: "I am very pleased with the progress made so far.

"We believe there are many convincing arguments for merger and there is already considerable support for this."

The proposal is part of wider plans to create three bodies from Wales's current seven health trusts - with one merger between Pontypridd and Rhondda and North Glamorgan trusts already approved.