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* UK GDP growth slows to 0.1% m/m in Feb from 0.8% in Jan

* Ascential up after confirming separation plans of certain assets

* FTSE 100 down 0.7%, FTSE 250 off 0.3% (Updates to market close)

By Devik Jain and Sruthi Shankar

April 11 (Reuters) - British stocks ended lower on Monday as data showed the economy slowed more than expected in February, intensifying worries about a cost-of-living squeeze.

Gross domestic product rose by 0.1% in February, missing the 0.3% rise forecast by economists in a Reuters poll and down from a 0.8% increase in January.

London's leading share index .FTSE closed 0.7% lower, pulling back from its strongest level in nearly two months, while the domestically focused FTSE 250 midcap index .FTMC declined 0.3%.

"The winding down of the UK's booster vaccine and Covid-19 test campaigns weighed on growth in February and will continue to do so for the next few months," James Smith, economist at Dutch bank ING said in a note.

"Combined with the cost-of-living crisis, falling confidence, and the presence of an extra bank holiday, we expect second-quarter growth to come in slightly negative."

Still, the FTSE 100 has risen more than 3% so far this year, outpacing its global peers on the back of gains in heavyweight commodity and banking stocks as oil and metal prices rallied on the Russia-Ukraine conflict and interest rate hikes from the Bank of England to tame inflation.

Meanwhile, the pound GBP=D3 flattened to $1.3033 by market close, not far from its lowest level against the dollar since November 2020. A weaker pound tends to boost the FTSE 100, which houses many international players that earn in dollars.

However, concerns related to the domestic economy have been reflected in the mid-cap index, which is down more than 10% in 2022.

Among individual stocks, Ascential ASCL.L climbed 2.1% after the events and analytics company confirmed a media report that it was in the early stages of evaluating the merits of a break-up of some of its businesses.

Energy services provider John Wood Group WG.L surged 12.7% after Jefferies upgraded the stock to "hold" from "underperform".

Weir Group WEIR.L slipped 3.2% after the engineering firm acquired Carriere Industrial Supply.
editing by Uttaresh.V, Subhranshu Sahu and Alex Richardson