Emoov founder Russell Quirk has branded OnTheMarket a flawed concept with silly anti-competitive rules and predicts the portal won't last more than 12 months.
In a video clip on YouTube, Quirk says the new portal is run by a cartel of estate agents looking to protect themselves against the inevitable change in the estate agent industry.
Quirk says there are several things consumers need to know about OTM. He says despite the new portal being touted as increased choice, it has only signed up 20% of agents so will only list around a fifth of all properties for sale in the UK.
He also criticised the portal's rules about forcing agents to drop either Zoopla or Rightmove, saying this means only half of prospective buyers will get to see a vendor's property.
Online agents are not allowed to join OTM but Quirk says Emoov would have joined if it was allowed as the move would fit in with Emoov's ethos to give consumers selling property maximum coverage.
You can see Quirk's video below.