* Risk aversion hits shares ahead of key rate decisions

* Losses trimmed after output data better than forecast

* Banks and commodity stocks fall

* Defensive telcos, food retailers advance

By Harpreet Bhal

LONDON, Nov 5 (Reuters) - Risk aversion ahead of key central bank policy decisions put pressure on Britain's leading shares around midsession on Thursday, with weakness in banks and miners offsetting modest gains in defensive telecoms and tobacco firms.

By 1109 GMT, the FTSE 100 .FTSE was down 0.4 percent, or 22.25 points at 5,085.64, with investors staying on the sidelines ahead of a decision by the Bank of England on interest rates and quantitative easing at 1200 GMT.

Miners were the biggest sector drag as metals prices retreated across the board on the back of a strenghtening dollar. Vedanta Resources (VED.L: Quote, Profile, Research), Xstrata (XTA.L: Quote, Profile, Research), BHP Billiton (BLT.L: Quote, Profile, Research), Rio Tinto (RIO.L: Quote, Profile, Research) and Kazakhmys (KAZ.L: Quote, Profile, Research) fell 1.7 to 4.1 percent.