HAMBURG, Germany-Aon Group Inc. has merged two of its German operations to strengthen business with midsize companies and attract more top industrial clients.

The merger of Hamburg-based Hudig-Langeveldt GmbH and Wesselhoeft Ahlers & Schues creates the third-largest broker in Germany. The combined Hamburg-based operation, which will be called Aon Deutschland GmbH, will have a staff of about 450 and gross revenues of more than 85 million DM ($51.7 million).

Wolf-Jurgen Thurnagel, chief executive of Aon Deutschland Holding, the parent of the combined German brokerage operation, says Aon's corporate identity is a key factor for expansion in the German market.

In September 1996, Aon acquired Wesselhoeft, Ahlers & Schues for an undisclosed sum. Hudig-Langeveldt, which Aon acquired in 1991, has bolstered its position in Germany through the acquisition of 10 midsize brokers since 1972, when it entered the German market from the Netherlands.

The merger will strengthen the two German brokers' core business with midsize companies.

Mr. Thurnagel said he expects that the combined operations will continue to be the broker of choice for midsize companies doing business in Germany.

In addition, Aon plans to use the combined operation for niche business.

The two Hamburg-based brokers are specialists in credit insurance.

The most important new strategic goal, however, is top industrial clients, Mr. Thurnagel said.

"Germany's top 500 are a major focus," he said.

"Aon is a single, closely knit global player. We have the advantage over loose configurations like the UNISON network (which includes top German broker Jauch & Huebener) because no one knows how long it will last," Mr. Thurnagel said.

For the time being, Aon does not plan any additional acquisitions in Germany, Mr. Thurnagel said.

With the broker's recent purchase of Alexander & Alexander Services Inc., Aon now holds 20% of Dusseldorf-based Jaspers Industrie Assekuranz.

Although Germany's market conditions have squeezed profit margins, Mr. Thurnagel expects the combined German operation's profits to increase about 10% in 1997 from last year.

Peter Wesselhoeft, chairman of Wesselhoeft Ahlers & Schues, will head Aon Deutschland GmbH.