The fight between Australia's two biggest real estate listing websites continues, with Domain Group chief executive Antony Catalano threatening legal action against competitor REA Group, owner of realestate.com.au.

Catalano accuses the digital property marketing company of deceptive and misleading behaviour. In a letter sent to REA chief Tracey Fellows on Thursday, Catalano said the company had failed to include Domain's traffic from mobile devices when comparing audience figures for the two rivals in presentations to investors, reports The Australian Financial Review. "When you include mobile app visits, traffic to our sites grew by 19 per cent, or over 55 per cent faster than your growth rate of 12 per cent over the same period," Catalano wrote on Thursday. "It is therefore our belief that the statements you made at the investor briefing and in subsequent media and investor comments are deceptive and misleading, and we would request that in future you reflect our comparative market positions honestly. Should you fail to do so, we will take action under Australian competition and consumer law."

Fellows responded saying REA stands by the figures reported.

Owned by Fairfax Media, Domain has been locked in a war of words with REA, which is 61.6 per cent owned by rival media company News Corp Australia, for the past 12 months. Last year, Catalano wrote an open letter to real estate agents around the country, rallying them to shun realestate.com.au because of the site's rising advertising prices. Yesterday he also sent a letter to agents elaborating on the dispute about audience share.