Two years have now passed since most of the office holders received a raise.

The tribunal said on Friday it would defer its decision until the second half of this year, to give it time to examine the latest labour market data and "movements in both private and public sector executive remuneration".

However, the tribunal's two members, business executives John Conde and John Prescott, confirmed their belief that significant increases were warranted for the heads of government departments and agencies, saying the tribunal "does not retreat from its assessment [last year] of the proper relative remuneration of those most senior offices".

The delay allows the Abbott government to avoid the awkwardness of overseeing pay rises for politicians at a time most federal public servants have gone almost two years without a raise.

The bureaucracy has been trying to negotiate more than 100 separate wage deals with its staff since early 2014 but no workplace has yet reached an agreement.

A federal backbencher presently receives a base salary of $195,130 a year while Prime Minister Tony Abbott receives $507,338.

Departmental secretaries' base salaries range from $454,454 to $561,974, while their total remuneration is between $649,220 and $802,820 (the highest figure is for Department of the Prime Minister and Cabinet head Michael Thawley). Their pay rose significantly as a result of a review of their responsibilities in 2011, which found they had been dramatically underpaid.

However, the last in a series of "catch-up" increases for secretaries was postponed before last year's tough budget, when Mr Abbott announced he would ask the tribunal to freeze salaries across the top tiers of government.

The tribunal said on Friday that "economic indicators and commentary over the past 12 months confirm that the wages environment is challenging and has slowed".

"It appears likely that this will continue, with general wage movements in the two to three per cent range or potentially lower."