Chancellor Gordon Brown does not have the ultimate power over changes to the pension system, according to the work and pensions secretary.
John Hutton said decisions over the looming pensions crisis would only be taken after "a grown-up, mature debate".
In an interview on GMTV, he said: "These are decisions for the government as a whole to take and that is quite clear."
Adair Turner's pension commission is due to publish its final recommendations into the future of pensions on Wednesday, and reports suggest Mr Brown has major concerns over plans to link pensions to earnings and raise the state pension age.
It is believed he opposes the report's predicted suggestion that the pension age be raised to 67 to pay for a restoration of the link between pensions and earnings.
Mr Hutton stressed that the chancellor was responsible for public finances and would play a key role in the debate.
But he added: "There will be a debate within government over the next few months about how we can structure these proposals.
"We are not going to take any risks with public finances and what emerges has to be a set of proposals the country can afford and are sustainable over the long term."
Meanwhile, Mr Brown is reportedly ready to risk confrontation with cabinet colleagues by using the pensions report as justification for scrapping a deal under which workers will continue to retire at 60.
He believes that Britain will have a two-tier workforce which is unacceptable to taxpayers if public sector workers retain this retirement age.