Chief Secretary to the Treasury Danny Alexander said that the highly coveted rating was not the "be all and end all".
His comments contrast starkly with those of the Chancellor George Osborne, who has emphasised its importance.
Labour pounced on the comments yesterday, saying that Mr Alexander was setting the scene for more bad news to come.
Rachel Reeves, the party's Shadow Chief Secretary, pointed to the fact that two of the three main agencies have put Britain on "negative" outlook.
She added: "Danny Alexander's comments suggest Ministers are worried about more bad news from the rating agencies if they continue failing to deliver economic growth.
"But instead of a change in rhetoric the country needs a change of course and a plan for jobs and growth."
At the end of last month Mr Osborne hailed the fact that the UK's AAA rating had been confirmed by one of the major credit ratings agencies.
At the time the Chancellor said that the announcement showed that the "world has confidence" in the Coalition's plans to cut the deficit.
But Mr Alexander insisted that "the right policies" were more important.