Newstalk ZB's Christchurch radio frequency has sold for nearly 8 million dollars after an online bidding war.

The 100.1 FM frequency was won by NZME. radio, which owns Newstalk ZB, for $7,820,922.

It's believed to be the biggest single auction in Trade Me history.

The auction was due to close at 9am, but a bidding frenzy forced the auction to close just over two hours later.

Radio frequencies in New Zealand are sold by the Government on 15 year fixed-term leases.