US President Donald Trump will meet later with European Commission President Jean-Claude Juncker to address a simmering row between the two key economies.
In initial deals, London's benchmark FTSE 100 index was down 0.1 percent at 7,702.66 points, compared with Tuesday's closing level.
In the eurozone, Frankfurt's DAX 30 was almost flat at 12,688.71 points and the Paris CAC 40 added 0.2 percent to 5,445.24.