LONDON, Oct 24 (Reuters) - Barclays said its profit for the third quarter dipped slightly from a year ago, nonetheless beating expectations as strong performance in its primarily U.S.-based credit cards business offset sliding revenue in its investment bank.

The British lender reported pretax profit for the period of 1.9 billion pounds ($2.33 billion), down from 2 billion pounds a year ago and above consensus analyst forecasts of 1.77 billion pounds.

The bank held off on any unscheduled returning of excess capital to shareholders, following a 750 million pound buyback in July that helped take the sting out of disappointing half-year results.

Barclays chief executive C. S. Venkatakrishnan said the bank would provide an investor update alongside its full-year results that will set out its capital allocation priorities and revised financial targets.

Barclays reported a 6% drop in income at its investment bank for the quarter, following a similarly downbeat performance at the half-year results update in July.

Revenue in its traditionally strong fixed income, currency and commodities division fell 13% as falling market volatility dampened clients' enthusiasm for trading.

($1 = 0.8151 pounds) (Reporting By Lawrence White and Iain Withers; Editing by Kirsten Donovan)