Barclays has so far paid £194m to settle a US-led probe into payments made to countries or people on a sanctions list.
The FTSE fell in early trading in reaction to losses on Wall Street overnight and a weak opening in European markets.
The Lloyds Banking Group has returned to profitability after posting a £1.6bn before tax profit in the first half of the year.
London's top stocks have given up some of yesterday's triple-digit gains in early trading, with the FTSE 100 down 0.72%.
Banks are once again leading the FTSE 100 gains in early trading, after a number of stocks soared upwards of 10% yesterday on the relaxing of Basel III rules.
Barclays, RBS and Lloyds shares have all rocketed today on news the Basel Committee plans to water down its capital and liquidity reform package.
British taxpayers stand to make a £5bn profit from insuring the toxic assets of RBS and Lloyds, despite not yet having paid a penny.
Investec's Alastair Mundy has sold out of Lloyds in his £1.57bn Cautious Managed and £344m UK Special Situations funds on fears the group runs the risk of becoming a ‘zombie bank'.
OPM Fund Management has bought its second reverse convertible product in two weeks, to benefit from volatility in the share prices of property companies.
Lloyds shareholders have made a £14bn claim against the Treasury and bosses at the banking giant over its controversial takeover of HBOS in 2008.