Shadow MPs are stepping up their opposition to the introduction on an emissions trading scheme as the Government admits Australia will "inevitably" enter recession and flags a third wave of economic stimulus measures this week.

The word "recession" was finally used by Prime Minister Kevin Rudd on Monday.

He acknowledged it would be "impossible" for Australia to avoid a further period of negative economic growth.

On Tuesday, Mr Rudd pointed to additional stimulus measures in next month's Federal Budget, and while not giving away many details, he stressed the emphasis would be on jobs.

But job losses are what the Coalition is worried about with the introduction of an emissions trading scheme during such torrid economic conditions.

Leader of the Nationals, Warren Truss, said that, with the Prime Minister's recession admissions, he should call for revised emissions trading scheme modelling from Treasury to reflect the current circumstances.

He said Treasury’s current modelling was produced when the global economy was predicted to grow by 3pc and continue to grow by at least 2.5pc over the next 10 years.

"…with the Government admitting that the economy is going into recession on its watch, Labor is still standing by its outlandish claims of how good an ETS will be for the country," Mr Truss said.

"The first new piece of modelling should be one that Labor has never released - the effect of its ETS on jobs."

Mr Truss said the original modelling also assumed that everyone else was going to sign up to similar schemes.

The Government has insisted it will stick with its timetable to introduce the scheme, expected to be after the Budget in May, with hopes it would be passed before the mid-year break in June.