Aon Corp , the world's largest insurance brokerage, reported a larger-than-expected quarterly profit as contributions from recent acquisitions helped offset a decline in commissions.

The company said commissions and fees from core operations fell 1 percent but recent acquisitions, mainly Allied North America that Aon bought in December, pushed up revenue by 2 percent.

Second-quarter net income attributable to common shareholders was $153 million, or 63 cents a share, compared with $149 million, or 50 cents a share, in the year-ago period.

Excluding items, the company earned 81 cents a share.

Total revenue at the company, which competes with Marsh & McLennan Cos Inc , rose 1 percent to $1.90 billion.

Analysts on average had expected the company to earn 75 cents a share, excluding items, on revenue of $1.87 billion, according to Thomson Reuters I/B/E/S.

Consulting unit revenue rose 6 percent to $317 million in the second quarter. Revenue from insurance brokerage services, which accounts for more than 80 percent of its total revenue, rose 1 percent to $1.59 billion.

Aon, which is also looking to grow its consulting business, agreed to buy Hewitt Associates Inc for $4.9 billion on July 12 to create the world's largest human resource services company.

Aon plans to integrate Hewitt with its existing consulting and outsourcing operation and sees the deal to add to 2011 and 2012 earnings.

Aon shares closed at $36.63 Thursday on the New York Stock Exchange.

(Reporting by Supantha Mukherjee in Bangalore; Editing by Gopakumar Warrier)