An Axa Insurance spokesman says the reviewed panel will be "substantially smaller" but refuses to divulge how many firms will survive.
A source at one of Axa Insurance's panel firms says: "We are getting ready for the Axa review that is going on at the moment.
"They are looking very hard at the firms they use for claims handling." Axa Insurance bought Guardian Royal Exchange last year. The Axa Insurance spokesman says the panel cuts are part of a rationalisation drive.
He says: "We have been looking at all areas, including the solicitors panel." None of Axa Insurance's claims work is handled in-house, but is outsourced to between 30 and 40 law firms across the UK.
The spokesman says: "There's no need to have that volume of people on the panel.
"Parts of the operation are using existing Axa people whenever they need a lawyer, and existing Guardian people are using Guardian lists."
He adds: "The law firms are probably waiting with baited breath."
The internal source reveals Axa Insurance's plan to canvas firms, holding face to face meetings to establish which firms have the most common ground.
The bulk of the work is in litigation, including motor insurance claims, fraud and debt recovery.
An industry source says: "It would be a substantial volume and a substantial fee value."
Europe's largest insurer Axa owns a controlling share in Axa Insurance, which is a subsidiary of Sun Life and Provincial Holdings. The results of the review are expected in April