Standard & Poor's maintained its triple-A rating for British sovereign debt on Friday but said that public borrowing was likely to be higher than the government has forecast and it might need more revenues from taxes.
Finance minister George Osborne has said that he intends to balance Britain's budget over the coming years without raising taxes. S&P—the only major ratings agency not to have cut Britain's AAA rating—said the tax base might need to widen.
"We expect that future consolidation may eventually look more to the revenue than the expenditure side," S&P said.
S&P also said Britain's economy would suffer if it left the European Union, something on which Prime Minister David Cameron's Conservative Party wants to hold a referendum if it continues to hold power after a national election in May 2015.