UK GAS-Prices ease as sterling strengthens, colder weather supports

(Releads on stronger sterling, updates prices)

* Sterling strengthens following upbeat UK data

* Colder weather expected, boosting demand

* Fears of Russian supply cut offer support

LONDON, April 8 (Reuters) - British wholesale natural gas prices slipped on Tuesday afternoon as sterling strengthened on upbeat British economic data, but prospects for colder weather checked the downward slide.

British factories expanded far more quickly than expected in February, official statistics showed, while separate surveys showed a strong first quarter for companies.

In response, sterling firmed about 0.4 percent. Strength in sterling makes gas priced in British pounds more expensive for holders of other currencies.

"Gains in prices seen this morning have reversed," a gas trader said. "A sharp gain in the value of sterling ... has contributed to this."

Gas for delivery on Wednesday fell to 51.00 pence per therm at 1400 GMT, down 0.70 pence from Monday's close. Further out on the curve, gas for delivery next winter was down 1.15 pence at 62.50 pence per therm.

Prices climbed on Tuesday morning (Frankfurt: TDM.F - news) in volatile trade, driven by fears tension between Russia and Ukraine could disrupt Russian gas supplies to Europe.

Russian troops are massed on the border with Ukraine, a major transit route for Russian gas to Europe.

According to data from National Grid (LSE: NG.L - news) , Britain's gas system was broadly balanced on Tuesday, with forecast flows of 200.3 million cubic metres (mcm) and demand of 202.2 mcm.

But meteorologists said they expected average British temperatures to drop towards the seasonal norm over the next two weeks, likely boosting demand.

"With cooler UK weather, prices could see better support around current levels, and the promised loss of so much Norwegian production for May does mean the market seems a bit tighter," Energy Aspects said in a research note on Tuesday.

Norway is planning several maintenance shutdowns in May, reducing available capacity, according to Norwegian pipeline operator Gassco. (http://flow.gassco.no)

Also supporting prices were high sendouts of about 36 mcm of gas per day from the South Hook liquefied natural gas (LNG) terminal, where the tanker Al Gharrafa is moored. Two further LNG tankers are due to arrive in Britain by April 15.

In Britain's power markets, prices for baseload (24 hours) delivery on Wednesday rose by 2.20 pounds ($3.65) per megawatt-hour to 41.20 pounds per MWh as wind power production was expected to decline.

($1 = 0.6020 British Pounds)

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(Reporting by Alexander Winning; Editing by Sonya Hepinstall)