A report expected to recommend severe pay cuts for Taoiseach Brian Cowen, his ministers and top civil servants, has been delayed until the end of September.

But Cowen and his cabinet are in for a shock on their return from their summer holidays as a recent report by international pay consultants Hay, which is conducting the current review, suggests they could face cuts of up to 40%.

In a review of pay levels for prime ministers, ministers and senior civil servants across eight EU countries by the Hay Group, Taoiseach Brian Cowen's salary of €231,700 was almost €40,000 ahead of the prime minister in Belgium and almost twice the €123,300 paid to the head of the Dutch government – two EU countries which it is understood will be used to benchmark our politicians' pay.

This would suggest a pay cut of 20% to 40% for Cowen, though politically this is considered unlikely to happen.

Ministers do not fare as well when compared to other EU countries, but at an average of €155,600, they are still paid €33,000 more than their counterparts in the Dutch government, according to the Hay report.

But heads of departments fare best of all when compared to their colleagues in 'comparable' EU countries. At a maximum of €216,900, a secretary-general in Ireland is paid over €75,000 per year more than comparable civil servants in the Netherlands and almost €23,000 more than those in Belgium.

In fact, senior Irish civil servants are the second best paid across the eight countries surveyed by Hay, including Germany and France. Only senior civil servants in the UK on €312,400 are better paid than their Irish equivalents.

In last April's budget, finance minister Brian Lenihan ordered a "review" of the salaries of the country's top public servants.

But unlike the last review in October 2007, which compared the pay of our senior public servants with top- level private sector jobs in Ireland, this time Lenihan ordered rates to be compared to the pay of politicians and senior public servants in other "comparable" European counties.

The review will also take account of the deteriorating economic and budgetary situation and will also factor in how top-level private sector salaries have fallen in the last 12 months.

In the last review, then Taoiseach Bertie Ahern was awarded a €38,000 increase, bringing his salary up to €310,000. Following intense public pressure, Ahern eventually and reluctantly declined to take all but 5% of the award.

"I believe pay at leadership levels in the public sector should be more in line with pay in other countries rather than with top-level private sector pay in this country," Minister Lenihan said in his April budget.

Lenihan wanted the review to be completed by July. But the Review Body on Higher Remuneration in the Public Sector, which is conducting the exercise, asked Lenihan for an extension to the end of September because of the extensive amount of work involved in comparing pay levels here with six other EU countries "of comparable size and scale", particularly those in the eurozone.

"Nothing is being ruled in or out" a spokesman for the review body said last week when asked whether a pay cut is possible in September.

Because public-sector salaries are closely interlinked, Lenihan also believes that these large salaries at the very top have inflated the overall public sector paybill, which now stands at €20bn, or well over a third of what it costs to run the country.

The spokesman would not say what EU countries have been chosen for the benchmark but confirmed it will be based on population and GDP.

However, it is understood that countries like Norway, the Netherlands and Belgium will be used as well as the UK, even though it is outside the eurozone.

All of the above countries are included in the Hay survey of top public servants pay produced last year. This placed Irish politicians and public servants near the top of the euro pay league, irrespective of the country's size.

But in what will be a major concern to our senior public servants, Hay also ranked jobs by their size – something it will also do for the pay report due in September.

While Taoiseach Brian Cowen is not that far behind the pay of Nicolas Sarkozy in France and Angela Merkel in Germany, he is graded at level 5 of nine levels while Merkel and Sarkozy, are graded 1.

In fact Cowen is graded at the same level as the Polish finance minister who is paid €44,600 a year – one fifth of Cowen's salary.

"Generally speaking, the jobs in the bigger countries (particularly the UK, Germany and France) tend to be higher paid than those in smaller countries (such as Netherlands and Norway). Belgium and Ireland do not reflect this conclusion. The pay level there is above average," noted the Hay report.

A spokesman for Hay said the report will be presented to government by the end of September.