By Simon Challis

LONDON (Reuters) - ICAP (IAP.L: Quote, Profile, Research), the world's biggest interdealer broker, said revenue rose 15 percent in its first quarter as it benefited from intense market volatility and it expected annual profit to be in line with market forecasts.

"ICAP has continued to benefit from higher than average levels of volatility as well as the investment we have made in recent years to broaden our business. We remain very positive about the outlook for the business," ICAP Chief Executive Michael Spencer said in a statement on Wednesday.

ICAP said it expected pretax profit for the year ending March 2009 to be broadly in line with the current average of analysts' forecasts, which it said was 375 million pounds. It made 330 million pounds in the year to the end of March 2008.

Spencer said the firm expected to deliver revenue growth of at least 10 percent this year, in line with the medium-term industry growth rate.

ICAP shares rose 2.5 percent to 428.5 pence at 9:20 a.m., among the FTSE 100 index's biggest gainers, as analysts said the statement would help ease market concerns that deleveraging at banks was hitting the broker's business.

"We see delivering double digit growth in revenue this year after an exceptional period last year is very commendable," said Numis Securities.

Spencer said the turbulent financial markets had seen continued high levels of activity in European interest-rate, foreign-exchange and energy markets.

ICAP's revenues from emerging markets were slightly down on last year's very strong first quarter, while growth in credit derivatives had slowed. But revenue from corporate bond markets had increased, it said.