Barclays reported pretax profits fell 9% to £1.66bn in Q1 2011, down from £1.82bn in Q1 2010.
The bank, which declared a dividend of 1p for Q1, said total net income had fallen 8% to £7.4bn, driven by the "impaired economic environment" and a higher charge to its own credit.
Adjusted profit before tax, excluding own credit and gains on acquisitions and disposals, rose 10% to £2bn.
Barclays also revealed it is expecting to shell out £100m to cover its bill for the upcoming bank levy, although this has not been included in the results.
It said: "The impact of the UK bank levy, for which legislation has not yet been enacted, is not reflected in these results in accordance with generally accepted accounting principles. The amount attributable to Q1 2011 is expected to be approximately £100m."
UK profit before tax rose 21% to £288m (2010: £238m), driven by a strong performance in reducing impairment and good growth in mortgage balances.
Meanwhile, Barclays Wealth's profit before tax was up 2% on the previous year at £46m. Strong income growth of 14% was driven by the high net worth businesses. However, investment management profit before tax fell to £24m, down from £29m in Q1 2010.
Barclays also announced in February it will close its advice arm, and pledged to send existing clients to IFAs.
Bob Diamond, Barclays chief executive, said the group had enjoyed a solid quarter of profitability.
"We have made a good start in 2011 in a challenging external environment," he said.
Earlier this year Barclays became embroiled in a Libor manipulation scandal. Authorities are investigating whether rules that prevent information-sharing among different parts of the bank were violated in communications between the bank's traders and its treasury arm.
Barclays said today the FSA and US authorities were assessing previous submissions it made to the BBA which sets Libor rates.
It said: "We are cooperating with the investigations being conducted by these authorities and are keeping relevant regulators informed. It is currently not possible to predict the ultimate resolution of the issues covered by the various investigations, including the timing and the scale of the potential impact on the Group of any resolution."
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