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London's benchmark FTSE 100 index won almost 0.5 percent to 6,307.86 points, as investors awaited the British government's budget update due at 1230 GMT.
In the eurozone, Frankfurt's DAX 30 added 0.2 percent to 10,958.40 points and the Paris CAC 40 also gained 0.2 percent compared with Tuesday's closing level to open at 4,830.22.
Equities had fallen on Tuesday with airlines and hotel groups hit by a US travel warning, and the downing of a Russian jet by Turkey.