Investors were also on tenterhooks before US President Donald Trump's summit with North Korean leader Kim Jong Un, and ahead of this week's European Central Bank and Federal Reserve interest rate decisions.

In initial trade, London's benchmark FTSE 100 index of major blue-chip companies was 0.3 percent ahead at 7,706.08 points.

In the eurozone, Frankfurt's DAX 30 added 0.4 percent at 12,816.32 points and the Paris CAC 40 gained 0.2 percent to 5,459.81, compared with the closing levels on Friday.