New Zealand captain Daniel Vettori says life bans should be imposed on players found to have fixed cricket matches, saying extreme steps must be taken to defend "the spirit of the game".

In his first public statement on allegations facing Pakistan cricket players, Vettori told the Sunday Star-Times newspaper that fans would question the validity of all results unless cricket quickly attacked corruption.

Vetorri said "if you're caught, you have to be banned for life". He said the allegations that Pakistan players bowled no-balls at predetermined times had undermined cricket's credibility. He hoped the current allegations against Pakistan players Salman Butt, Mohammad Asif and Mohammad Amir were untrue.