LONDON (Reuters) - Energy supplier RWE npower, a subsidiary of German utility RWE (>> RWE AG), will cut British gas tariffs by 5.1 percent from Feb. 16 after a fall in wholesale costs, the largest cut made so far this year by Britain's biggest six energy providers.

RWE npower's customers will see their bills go down by an average 35 pounds per year on the back of the lower tariff, the company said in a statement.

Wholesale crude and gas prices in Europe have tumbled due to a global supply glut, reducing some of the energy purchase costs utilities incur.

"If there are further falls in wholesale prices, we will keep these under review to see if we can cut further," said RWE npower Chief Executive Paul Massara.

Finance minister George Osborne, gearing up for a May general election, urged energy companies earlier this month to pass on those savings to customers, saying action could be taken if they failed to do so.

RWE npower's cut is slightly steeper than reductions announced so far by rivals E.ON (>> E.ON SE), Centrica's (>> Centrica PLC) British Gas and Scottish Power (>> Iberdrola SA) who have cut tariffs between 3.5-5 percent.

This leaves EDF Energy (>> EDF) and SSE (>> SSE PLC) open to cutting their customer prices.

(Reporting by Karolin Schaps, editing by William Hardy)

Stocks treated in this article : EDF, Iberdrola SA, RWE AG, E.ON SE, SSE PLC, Centrica PLC