The competition regulator says it has concerns about a proposed merger between Apollo Tourism and Tourism Holdings because of the potential market power in Australia in the campervan rental market where they are already the two largest players.

Tourism Holdings, a large New Zealand company in campervan rentals, operates brands in Australia including Maui, Britz and Mighty Camper. Apollo, which is listed on the ASX, operates rental brands including Star RV, Apollo, Cheapa Campa and Hippie Camper.