NEW YORK (Bloomberg) - Aon Corp., the biggest insurance broker, said customers pinched by the slowdown in US economic growth are cutting back the amount they spend on coverage.

"The economy is obviously impacting our clients," CEO Gregory Case said on Friday in an interview. Customers are "under pressure" to reduce costs, he said.

Mr. Case is cutting jobs and office space as a decline in business policy rates squeezes the commission brokers make for matching insurance buyers and sellers. Second-quarter risk and brokerage services revenue in the Americas, Aon's biggest market, fell one percent, excluding the impact of acquisitions and foreign exchange, the company said yesterday. That compares with a 24 percent gain in Europe, the Middle East and Asia.

"The economy is weak," said Chuck Hamilton, a Nashville, Tennessee-based analyst at FTN Midwest Securities Corp. "So it's not just rates but also volume" that is declining in the US.

Aon fell 97 cents, or 2.1 percent, to $44.83 at 4.15pm in New York Stock Exchange composite trading. The Chicago-based company has declined six percent this year, compared with the 5.7 percent gain by Marsh & McLennan Cos., the No.2 broker.

Fees were pressured in the second quarter as construction companies and private equity clients made smaller deals, Case said earlier on a conference call with analysts.

Second-quarter net income rose to $1.13 billion from $240 million after the company booked a gain on the sale of Combined Insurance Company of America to Ace Ltd. Aon is buying back stock with the proceeds of the divesture and has said it will consider acquisitions to boost its brokerage.