Competitor OnTheMarket allows its members to list on only one other site. Many have opted for rival Rightmove, contributing to Zoopla losing around 25 percent of its agents in around a year.

But on Wednesday Zoopla said it had added 213 new branches, taking its total to 12,556 at the end of July.

Chief Executive Alex Chesterman, who said on Wednesday he would stay at the firm which floated in June 2014 for at least the next four years, told reporters he expected Zoopla would continue to attract more estate agent branches.

"As every week and every month passes...as long as this restrictive rule (from OnTheMarket) stays in place which damages both the agent and the homeseller, we expect to see more and more agents return to us over the coming months," he said, without giving further details.

The firm also said price comparison service uSwitch, which it completed buying in June, was trading well following the acquisition.

(Reporting by Costas Pitas; editing by Susan Thomas)