OnTheMarket chief Ian Springett has cast doubts on Zoopla’s inventory.

His remarks follow yesterday’s trading update by Zoopla.

Springett said: “It is hard to reconcile the property stock claims of Rightmove and Zoopla Property Group.

“Rightmove recently reported a 10% increase in UK residential listings since the start of the year to 1.1m, claiming to display 50% more than any other portal.

“Yet Zoopla Property Group stated today on its UK sales and rental search pages that it has 662,636 properties for sale and 215,652 properties for rent.

“This gives a total figure of 878,288.

“Moreover, searches conducted in the last 24 hours on the Zoopla portal show UK (England, Scotland and Wales) sales and lettings properties, including Sold Subject to Contract, Let and Shared Accommodation, total just 675,540.”

Springett also said that OnTheMarket is continuing to grow.

He said: “Zoopla’s trading update only serves to underline the success and progress of OnTheMarket in continuing to disrupt the property portals market.

“Its tepid growth of 213 agent branches since its April 2015 update is a drop in the ocean in the context of its 23% loss of agents (which equates to 3,812 agents) between 30 September 2014 and 31 March 2015.

“The fact is that Zoopla has lost overall share of agents and traffic as OnTheMarket has become established and as the overwhelming majority of our members retain the dominant market leader as their other portal.

“Contrary to suggestions made by Jefferies (joint sponsor of ZPG’s IPO last year), our one other portal rule remains in place.

“OnTheMarket was described six months ago by Alex Chesterman as a ‘short-term event’ but ZPG’s own trading update paints a very different picture.

“Support for OnTheMarket continues to increase daily.

“With such a strong desire for it to succeed from agents all across the UK – and a substantial growth in its traffic figures to more than 5.2m visits in July – we are confident  that OnTheMarket is here to stay and that we can ultimately achieve our objective to develop a proper alternative to the market leader.”