LONDON, Feb 19 (Reuters) - British gas prices rose slightly on Tuesday morning as colder weather was expected to raise heating demand for the rest of the week and imports of liquefied natural gas (LNG) were dwindling.

Gas for delivery the next day traded at 67.50 pence per therm at 0920 GMT, up 0.25 pence since Monday morning, and prices for within-day delivery were also up 0.25 pence to 66.85 pence a therm.

British spot power prices were also down, with contracts for baseload (24 hours) delivery on Wednesday trading down 0.3 pounds per megawatt-hour (MWh) to 50.70 pounds a MWh.

Analysts said that the price rise was a result of colder weather moving into Britain by Wednesday.

'It's getting cold again, and that that will lift heating demand and prices,' one gas trader said.

Britain's Met Office said that it expected maximum temperatures to drop from 10 degrees Celsius on Tuesday to 5 degrees on Wednesday and 3 degrees on Thursday.

'Brisk easterly winds will make it feel very cold,' the Met Office said.

Traders also said that falling import volumes of LNG to Britain were having a bullish effect on prices.

'Asian LNG prices are now so high that we cannot compete in Europe anymore so the Qataris are sending all their ships East,' another gas trader said.

Asian spot LNG prices have risen towards $20 per million British thermal units (mmBtu), a four year high and up from around $13 per mmBtu in Q4 of last year.

Despite the bullish sentiment, National Grid data showed that Britain's gas demand was well covered by supplies.

Gas demand was expected to be 316.1 million cubic metres (mcm) on Tuesday, 2.5 percent above the seasonal norm, but with flows seen at 335.9 mcm the system would be oversupplied by almost 20 mcm.

Further out on the curve, prices for gas deliveries next summer also remained high despite dipping below 64 pence a therm.

Trading around 63.85 pence, the contract remained well above all its 50, 100 and 200 exponential daily moving average values of 62.89, 62.29 and 61.77 pence a therm respectively, and French bank Societe Generale said in a research note that it recommended selling summer gas prices.

'We remain more bearish for the future curve (and) recommend selling NBP Summer 13 as we believe the forward curve has not taken into account the gas already 'pre-paid' by European companies to Gazprom in 2009-2012,' the bank said.

'No growth in European gas demand this year and increased take-or-pay volumes are likely to weigh on NBP gas prices, especially over the summer,' it added.

(Reporting by Henning Gloystein. Editing by Jeremy Gaunt.)

(henning.gloystein@thomsonreuters.com)(+44 207 542 6659)(Reuters Messaging: henning.gloystein.reuters.com@reuters.net)

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