Fiscal rules may have to be relaxed after data on Friday showed public borrowing at record levels, threatening to breach the restrictions the government set itself on how much debt it can take on.
Public sector net borrowing for the first quarter of the financial year was 24.4 billion pounds - the biggest quarterly figure since records began in 1946.
The current budget deficit for the period was 20.4 billion pounds, also a record high.
"Horrific, absolutely horrific. Net borrowing so far this financial year is almost 10 billion pounds above the same period last year, which suggests that the full year figure is going to be way, way above official government forecast," said Investec chief economist Philip Shaw.
As chancellor, Brown established two rules to govern public finances - that the government only borrows to invest over the economic cycle and that public debt be limited to a prudent and sustainable level, defined as 40 percent of GDP.
Public debt is running close to 40 percent and analysts say the government could break the limit as the economy is slowing and there is greater pressure to spend.
Friday's Financial Times said Treasury officials were privately working on plans to reform the rules and this could be announced in the pre-budget report in the autumn, and possibly allow for greater borrowing.
"We have not reached any decision on that," Chancellor Alistair Darling said on BBC Radio, adding the government has long said the rules were kept under review.
He said government borrowing was still lower than in many other countries and that it was right that it should rise in a downturn.
However, suggestions that the government might be about to relax its rules to allow more borrowing spooked markets.
