Scrap metal dealers and exporters say soaring commodity prices are bringing challenges to an industry that's worth $2b a year to the New Zealand economy.

One person has been arrested and four remain on a ship which Greenpeace boarded to prevent it from being unloaded in New Plymouth.

Tower, the insurer controlled by Guinness Peat Group, may return capital to shareholders, chairman Tony Gibbs told the annual meeting.

World dairy prices have continued to surge in Fonterra's latest online global dairy auction, rising 7.2 per cent overnight.

Equities on Wall St were up overnight, lifted by better-than-expected earnings from Exxon Mobil and a pick-up in US consumer spending that surpassed forecasts.