The firm is thought to be launching a service in early 2010 which is similar to one launched in Australia earlier this year. Under that model, estate agents can list properties for free using images and maps from Google.
Ed Mead, commercial director at Douglas & Gordon, said that Google had discussed its UK plans with estate agents including his own firm.
He added: “If the proposed system stays free, Google could pose a serious threat to the money which newspapers and property websites receive from advertisements and from charging estate agents to list properties.”
Laura Scott, spokeswoman at Google, did not deny the speculation but said the company would not comment on it.
Miles Shipside, commercial director of Rightmove, said: “Should Google announce anything, we are confident that people will continue to see the value in our services.”
Following the speculation, Rightmove became the worst-performing stock on the FTSE 100, slumping more than 10% to 499.9p by the end of trading last Thursday.
