UK's Scottish Power to increase dual-fuel prices by 7.8 pct

(Adds detail, background, Centrica (Frankfurt: A0DK6K - news) freeze)

LONDON, Feb 10 (Reuters) - Britain's Scottish Power will raise its duel domestic gas and electricity prices by 7.8 percent, it said on Friday.

The move follows a similar price increase announced by Innogy-owned Npower last week, and EDF (Swiss: EDF.SW - news) Energy, the UK arm of French utility EDF (Paris: FR0010242511 - news) , last year.

Fellow ‘big six’ energy supplier, Centrica owned British Gas, said on Friday it would freeze its standard tariff until August.

Britain's energy companies are under close scrutiny from the government, after sector regulator Ofgem said earlier this year it did not see a case for power companies to significantly increase their prices.

Scottish Power, owned by Spanish utility Iberdrola (Amsterdam: ID6.AS - news) , said its electricity prices will increase by an average of 10.8 percent and gas prices by an average of 4.7 percent from March 31.

The company said the rises were needed after an increase in wholesale gas and electricity prices, decarbonisation costs and the government's smart metre upgrade scheme.

Around one third of Scottish Power customers, or 1.1 million households, will be affected by the change.

Britain's other big six suppliers are SSE (LSE: SSE.L - news) and E.ON .

(Reporting By Susanna Twidale; Editing by David Goodman and Susan Thomas)