UK banks are borrowing billions of pounds each month and may be forced to seek yet more support from the government, an economic think-tank warns.
The FTSE 100 has fallen 0.3% or 16 points to 5,413.5 in early trading after America's Federal Reserve said overnight there were "widespread signs of deceleration" in the US economy.
The FTSE 100 fell 0.85% or 46.36 points to 5,392.83 this morning with Barclays among the biggest losers.
Barclays is set to name its investment banking boss Bob Diamond as successor to current chief executive John Varley.
Barclays Bank violated US sanctions in dealings with Cuba, Iran, Libya, Sudan and Burma, court papers have revealed.
Prudential's 1.5% rise in early trading, following better than expected first-half profits, helped the FTSE edge 0.3% higher to 5257.79 points.
The FTSE 100 opened in positive territory as strong results from majority-nationalised bank RBS crowned off a largely impressive results week for the UK banking sector.
Barclays has so far paid £194m to settle a US-led probe into payments made to countries or people on a sanctions list.
Barclays has posted profits of £3.95bn for the first half of 2010, up 44% on the same period last year.
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.