Second-quarter German and French GDP reports eased concerns about the euro zone's two biggest economies, but the region as a whole contracted over the three months, supporting the case for ECB action to bring down borrowing costs for some countries.
"We had a bit of positive news in that GDP data from both Germany and France were a bit better than expected," said Richard Hunter, head of equities at Hargreaves Lansdown Stockbrokers.
"I don't (expect) it changes the fact the ECB still will need to intervene to move towards some sort of resolution of the situation."
Britain's FTSE 100 index was up 32.41 points, or 0.6 percent, at 0901 GMT, lifted by a rally in cyclical oil and mining shares, as well as banks.
But results from Irish-based building materials group CRH were a reminder of dire economic conditions in Europe, leading the company to indicate stagnant annual earnings and sending its shares down 4.9 percent to the bottom of the index.
"The results and outlook reflect a more cautious (and realistic) view of the European construction sector with American markets also showing some signs of moderation from the strong first half," Davy Research said in a note.
"While the company continues to have one of the strongest balance sheets in the sector and its robust cash generation will continue to support an unchanged dividend, the valuation is pricing in an imminent recovery in construction markets which at the moment is difficult to see."
HIGH STANDARDS
Insurer Standard Life, up 5.1 percent, was among top risers after unveiling a forecast-beating 15 percent rise in its half-year profit thanks to cost cuts and strong growth in Britain.
Takeover speculation sent water company United Utilities 3.4 percent higher after press reports suggested it could become the target of an offer worth around 900 pence per share, compared to a 689 pence closing price on Monday.
The Daily Mail wrote that an international infrastructure consortium, including Canadian pension fund Ontario Teachers as well as Qatari and Abu Dhabi funds, is working on a break-up bid, while The Daily Express cited interest from private equity group KKR and China Investment Corporation.