Moody's Investors Service last night said if there is no progress in the US on increasing the country's statutory debt limit, it expects to place that government's rating under review for possible downgrade in the next few weeks.
The US treasury is battling to slash spending after the country's national debt soared to $14trn, reaching a self-imposed limit set by Congress last century.
The UK government borrowed less than expected for the financial year to 1 April, posting a total of £141bn.
Moody's has downgraded Portugal's government debt two more notches because of 'subdued' growth prospects.
Portugal has raised €750m (£641m) in a successful Government bond auction, following in the footsteps of other southern European nations.
Greece sold more debt than expected today as investors snapped up the issuance of short-term government bonds.