Top managers at hospital in Wales have an average salary of nearly �110,750 - around �12,000 more than their counterparts in London.

It does call into question whether there's any openness, honesty or integrity about the process in which they get their pay awards David Galligan, Unison

The report, compiled by Incomes Data Services, also claims information about how senior NHS leaders are awarded their money is becoming harder to track down.

Health unions say the pay awards should be more closely tied to performance on issues such as waiting lists.

NHS leaders in the north of England and Yorkshire have the next biggest pay cheques with an average income of �107,500, followed by those in Trent with �105,000.

Chief executives in London are only mid-table with average earnings of �98,000.

The survey found up to a quarter of the managers could have landed rises of 20% or more.

'Worsening'

David Galligan, Head of Health in Wales for the public services union, Unison, said he was concerned by the extent of the pay rises and wanted to see more transparency in the system.

"I find it slightly alarming that there is such a disparity within the figures - there has been confusion about what chief executives do get paid recent over years," he said.

"It does show that, certainly there's a worsening effect being felt in Wales in terms of waiting lists when you compare it with chief executives' salaries.

"The difficulty is, these figures talk in terms of averages but I'm conscious that the Welsh Assembly Government has been expecting senior managers' pay - and that would include chief executives' - to be in line with everybody else's pay movement - 3.6% perhaps in a good year.

'Transparent'

"If it's going beyond that, then it does call into question whether there's any openness, honesty or integrity about the process in which they get their pay awards."

He dismissed the argument that the health service in Wales - which tends to have larger NHS trusts than the average for England - has to paid good money to attract and keep quality senior managers.

He said there would be no difference in the quality of candidates for chief executive posts in London than in Wales.

"It just goes to show the whole process needs to come into the 21st Century and be open and transparent."

But Welsh NHS Confederation Director Richard Thomas described the Incomes Data Services report - which talks of a "fog" enveloping the information available on pay rises for top managers - as misleading.

Nurses

He said chief executive salary increases in Wales were linked to those other staff in the relevant NHS trust.

"We must attract and retain chief executives of the highest calibre and the salaries of chief executives of health trusts in Wales are in line with other public bodies."

The figures come as more than one million NHS workers consider whether to accept a new pay deal which will see salaries increase by at least 10% over the next three years.

Last year, nurses were awarded a 3.7% pay rise.