The government received more income than it spent in January, posting the highest surplus for four years following a drive to cut public spending.
It is far more likely the UK will retain its prized triple-A status than be downgraded, according to bookies.
Ratings agency Moody's has warned it may cut the credit ratings of 17 global banks and 114 European financial institutions as strains on the financial system increase.
Markets have slipped into the red in early trading as Moody's negative outlook for the UK's AAA credit rating weighed on sentiment.
The UK's prized triple-A credit rating was under threat last night after US ratings agency Moody's put it on negative outlook, citing pressures from the eurozone.
Credit rating agency Moody's has placed Tesco's long-term debt rating under review for a possible downgrade following its recent profit warning.
Ratings agency Moody's has warned the UK's prized AAA rating is at risk from the eurozone crisis despite the austerity measures taken to help retain its current status.
Barclays was among six global banking groups to be downgraded by Fitch last night, with the ratings agency pointing to challenging financial markets.
London's leading share index has made a subdued opening in early trading, with investors returning cautiously to stocks after yesterday's sell-off.
Struggling Hungary has moved to raise its benchmark interest rate from 6% to 6.5%, the highest ever level seen in the European Union, in order to protect its currency.