The row between Zurich and Folgate has escalated. The insurer has sent letters to some of Folgate's clients naming brokers they can transfer their business to if they wish to continue their relationship with Zurich.

It is understood that the letters were sent after the meeting on 7 July between Folgate chief executive Andy Homer and Zurich's UK general insurance chief executive Ian Stuart.

Sources said that Alexander Forbes, Perkins Slade, Henderson Insurance Brokers and Lark Insurance Broking Group were among the brokers named in the letters, dated 12 July and 13 July, and signed by Zurich's UK commercial head of market management, David Smith.

A Zurich spokeswoman confirmed it had sent the letters. She also confirmed that Alexander Forbes, Perkins Slade, Henderson and Lark were four of the brokers named in the letters. "What we are doing is offering them choice," she said. "We are working with 40 brokers across the UK."

A spokesman for Alexander Forbes said its involvment was a "local, informal branch arrangement".

Lark and Henderson were not available for comment. Perkins Slade chief executive David Slade declined to comment, but in a letter to Insurance Times (15 July), Slade defended Zurich's strategy. In the letter Slade said: "It is not for me to get involved in the dispute between these two large organisations.

"Working with brokers who are looking for something more than the cheapest price from their insurer, Zurich has adopted a hugely aggressive approach."

Homer said that the meeting with Stuart over the personal and professional lines relationships would be followed by further discussions.

But sources said this could change after September, when many of Folgate's commercial accounts with Zurich come up for renewal.

"It depends on how aggressively they attack Folgate."