Benfield is facing mass resignations from its facultative reinsurance business including head of the division Elliot Richardson.
Benfield has confirmed that 20 people have resigned from the Facultative Solutions team, but industry sources say that more than 50 have handed in their notice.
The number could rise to as many as 90, according to a broking source.
The resignations follow Richardson's high-profile departure earlier this month. He will take over as head of Aon's global cedant facultative reinsurance activities.
It is understood that some of the 105-strong team at Benfield, which work out of 14 offices worldwide, could join Richardson at Aon.
Aon's coup comes after a lengthy recruitment programme by the rival broker in the cedant facultative reinsurance area.
Michael O'Halleran, chairman and chief executive of Aon Re Global, said: "We have already made considerable progress in cedant facultative reinsurance. This appointment demonstrates our commitment to investing further in our capability to serve our clients in this important area of business, which has high growth potential."
