Lloyd's brokers have lashed out against underwriters' requests to slash commission.
The appeal to cut brokerage by an average of 2.5% follows large rate rises in a hardening market.
But John Bannerman compliance director Neil Golder was outraged by the suggestion.
"We are the unpaid agent of the insurer," he said. "Why should brokers take all the costs of trying to generate business?"
Commissions for placing business are often the major source of revenue for intermediaries. Brokers usually take a percentage of the premium, which can range from 3% to over 50% depending on the nature of the risk.
Now brokers are being asked to take cuts in the amount of money they earn on each deal placed.
In theory, as rates have risen by around 30% to 50% across the board, intermediaries will bring in the same amount, if not more, per transaction.
Lloyd's spokesman Adrian Beeby confirmed requests for cuts were taking place.
"As rates are going up, brokerage is going down," he said.
"If a broker tells a client costs have doubled, he has to say he will reduce his commission. But he may be earning more anyway."
Golder said intermediaries are entitled to their share as they have to pass on tougher contract conditions and larger premiums to the insured.
"It is much harder to justify underwriters' terms to clients," he said. "The insurer does not have to do this."
Golder added insurers have used brokers as a "barricade" and intermediaries felt "aggrieved" that their commission is under strain.
Guy Carpenter deputy chairman, Mark Hewett, said the pressure had not yet reached reinsurance brokers.
But he added: "We would resist any such suggestion strenuously. We expect to operate by those same terms of trade."