The CBI has broadly welcomed the chancellor's pre-Budget statement but said it remains "concerned" about the outlook for Britain's public finances.
The CBI says the chancellor's growth forecasts remain "optimistic"
CBI director-general Digby Jones said Gordon Brown was right to raise borrowing "rather than go for spending cuts or tax increases".
But he said the medium-term economic outlook for the UK remained "a worry".
"Tax receipts are lower than expected and growth forecasts still look too optimistic," Mr Jones said.
The Institute of Directors (IoD) and the British Chamber of Commerce also voiced concerns about the chancellor's forecasts.
In his pre-Budget speech to the House of Commons, Mr Brown said Britain had met its growth target for 2003, with growth of 2.1%.
The chancellor added that growth targets for 2004 and 2005 - of between 3% and 3.5% - remained in place.
But IoD director George Cox said: "If his growth projections are not met he could be forced into imposing higher taxes which would be unwelcome and would have a serious negative effect on the economy."