NZX's plans to base its future growth on derivatives have taken a serious knock.

Two big power suppliers have blamed the Emissions Trading Scheme for price rises which will add an average $5 a month to electricity bills.

Mercury Energy blames the Emissions Trading Scheme for its planned increase in prices from July.

Meridian Energy and DOC have filed a joint memorandum in the Environment Court requesting the appeals relating to the Mokihinui hydro proposal be put on hold.