Gas prices are going up for Contact Energy Customers.

It will increase between 11 and 49 dollars a year.

But Contact says it's not its fault.

Spokesman Shaun Jones says gas distribution and transmission companies charges have gone up.

"From 1 December we are increasing the prices that customers pay for gas, to account for changing network and distribution charges from PowerCo, GasNet and Vector and are included in our customer's bills."

Contact Energy says the transmission price increases vary across geographical regions.

Shaun Jones says there are no changes for customers who use bottled gas.