Winter weather set to move into Britain from Monday evening

* Frosty outlook pushes up UK gas prices

* Cold weather could last for two weeks

LONDON - Britain is set to see the first winter weather from Monday evening as cold and strong northwesterly winds bring frost and ice, pushing up power and gas prices, and meteorologists say the cold weather could last for over a week.

Britain's Met Office has issued a yellow weather warning (its lowest) for northern parts of the country as wintry showers are expected to spread south.

"The first cold plunge of the season will bring air which has originated over the Canadian Arctic. This air mass will contain frequent showers, which will fall as snow over hills, and at times to low levels, especially in heavier bursts," the Met Office said.

Cold weather lifts natural gas and electricity demand, and as a result Britain's wholesale spot gas prices rose to 70.45 pence per therm on Monday morning, their highest level since last April when an unusually long winter almost depleted Britain's gas reserves, triggering price spikes.

Meteorologists said that the cold weather could last until the weekend and beyond.

"There will be quite cold weather with frequent overnight frosts as a high will stay in position right over the UK (for the weekend), bringing cooler than normal conditions," said Lars Elgeskog, meteorologist at Sweden's weather institute SMHI, adding that chilly conditions would persist for most of next week.