Consumers were last week given hope that their energy bills may soon fall, after Scottish Power cut the cost of one of its tariffs by 10%.

Consumer groups said it was the “shape of things to come”, with reductions of 10%-15% expected across the board in the coming months.

Scottish Power cut the cost of gas on its Price Sure fixed energy plan from Monday. Even though the plan is fixed, existing as well as new customers benefited from the reduction, with the average bill down by £81 from £1,210 to £1,129.

The tariff, originally launched on November 27, has a £30 exit penalty for electricity and £50 for dual fuel, if you leave before January 31, 2010.

Will Marples at the comparison firm Uswitch said: “We expect suppliers to take a cautious approach to bringing household energy prices down. They will be concerned that wholesale prices could move upwards again, eating into margins.

“To mitigate this risk, they are likely to opt to introduce cuts in two stages, making an initial reduction of 10%-15% in the run-up to spring 2009, followed by a second cut of a similar or smaller level later on in the year.”

Wholesale gas and electricity prices have fallen 40% from their 2008 peaks, as oil has plummeted from a high of $147 in July to around $40 at the end of the year.

However, crude has rebounded in the past week due to tensions in the Middle East, and the Russia-Ukraine gas supply row. Gas monopoly Gazprom cut supplies through Ukraine on January 1 in a dispute over debts — a worry for European consumers who depend on Russia for a quarter of their natural gas.

This could limit energy firms’ willingness to pass on bigger cuts, consumer groups said, as the dispute pushed up wholesale gas prices.

Gareth Kloet at comparison site Confused.com said: “While the UK imports only around 2%-3% of its energy from Russia, the recent crisis highlights the need to secure our own supply capabilities, as almost 40% of our total supply is imported from Europe. It is difficult to understand how we can gain control of energy-price fluctuations in the UK until we significantly reduce the amount of gas we import.”

Nevertheless, analysts are still expecting modest price cuts in the coming months. Joe Malinowski of the energy price-comparison website TheEnergyShop.com said: “Our analysis of forward wholesale prices and energy suppliers’ costs suggests that there is scope for a cut of 15% on standard gas prices \ and a 10% cut in electricity prices \.”

Uswitch has calculated that a 10% cut in gas and electricity prices would shave £129 off the current average bill of £1,293, taking it down to £1,164.

However, this would still leave bills £252 or 28% higher than the average £912 households were paying at the beginning of 2008.

“The prospect of £129 coming off the average household energy bill within the next few months is welcome, but moving to a competitive energy plan could save up to £350. This is something consumers can do for themselves today,” said Marples.

Scottish Power’s Price Sure plan is now cheaper than its standard tariff, but analysts said consumers should not be tempted to fix.

Malinowski said: “While we are strongly supportive of Scottish Power’s early move, we do not believe fixing energy prices at the current time is the right thing to do, even if the premium is as low as this one.

“In a falling market the best move is to go for the cheapest variable-rate deal. In this respect British Gas’s WebSaver 1 tariff not only guarantees an immediate saving but also further savings if British Gas cuts its standard prices by more than 5%. That’s the best deal to go for at the current time.”

The British Gas tariff costs an average of £1,059 for dual fuel assuming you pay by direct debit.