The ''extraordinary'' cost of accessing the national broadband network will limit the number of people who choose to use it, the opposition spokesman on communications, Malcolm Turnbull, has warned.

Mr Turnbull, who has yet to finalise the opposition's policy on broadband, signalled the Coalition was unlikely to make any dramatic change to its approach to rural broadband in response to the federal election result. Yesterday he challenged the government's central argument that the broadband network would benefit consumers and competition.

Opposition spokesman on communications, Malcolm Turnbull, says $65 a month will keep most off broadband. Credit:Wayne Hawkins

The government-owned NBN Co is likely to charge retailers about $35 a month. He predicted this would result in customers paying an average of $65 to $70 a month.

''That is higher than most people are paying now. So there is no reason to believe that the NBN will deliver cheaper broadband. It certainly will deliver faster broadband than many people are getting at the moment, but at an extraordinary cost,'' he said.