Small businesses prepared to shop around and switch provider may be able to avoid energy prices doubling as the cost of wholesale gas soars.

According to comparison site Make It Cheaper, many firms face annual renewal rates of 24p/kWh for electricity and 6p/kWh for gas compared to 12p and 3p this time last year.

This means companies coming off one-year fixed tariffs - the minimum fixed-term contract for non-domestic or industrial users - will see energy bills double while those coming off two, three or five-year deals will face even greater increases.

But business-only comparison site Make It Cheaper claims companies that avoid the rolling cycle of ‘assumptive renewal' - where suppliers assume businesses will enter another contract unless they hear different - could take advantage of new customer rates that are around the same price as contracts fixed a year ago.

"Serve notice in time and you can take advantage of ‘new customer' rates which are around half the ‘default' rates for business electricity and gas," said Jonathan Elliott, managing director at Make It Cheaper.

"But you will need to act during your renewal window, which can be as narrow as a week and often months before your current contract is due to expire.

"Check the small print for details as these are not at all like domestic contracts and ignore your supplier's renewal letter at your peril. Failure to act means that you are automatically, or assumptively, tied-in against your will for up to another two years."

The price of electricity and gas has now increased for a record 10 months in a row.

The Baseload Year Ahead price in May 2008 was £76/mWh, two-and-a-half times greater than the January 2007 figure of £29/mWh.