Gull New Zealand says BP's price tweaking practices come as no surprise.

A leaked email from BP shows the company told petrol stations in the Wellington region to put their prices up, to counteract falling sales in Otaki.

Gull New Zealand general manager Dave Bodger says the move doesn't appear out of the ordinary.

"Oil giants like putting up the prices.

"If I go back to my sixth form economics, [we learnt] there are big guys, and the best way for them to make money is to put the prices up."

Legislation's currently before Parliament that would give the Commerce Commission greater powers to obtain commercial information from petrol companies.

LISTEN ABOVE AS DAVE BODGER SPEAKS WITH MIKE HOSKING