LONDON (TheDeal) -- Oil stocks led London markets higher on Wednesday as Anglo-Dutch oil producer Royal Dutch Shell (RDS.A - Get Report) embarked on its biggest deal in over a decade.

The FTSE 100 advanced 0.47% to 6,994.70 as investors welcomed Shell's agreement to buy U.K. energy company BG (BRGYY) for about £47 billion ($70 billion) in cash and shares. But the picture was mixed on the mainland, with the CAC 40 inching up 0.16% in Paris to 5,195.56 and the DAX back-pedalling 0.21% to 12,098.44 by late morning.

Oil stocks stole the show after Shell announced an agreement to pay 383 pence in cash and 0.4454 of Shell's B Shares for each BG share, equal to about 1,367 pence a share or about 50% of the target's Tuesday close.

On Wednesday, BG shares soared more than 35% while Shell was down 2.5%. The momentum lifted other energy producers including Tullow Oil (TUWLF) and Ophir Energy (OPGYF), up 10.76% and 7.76%, respectively.

Shell, which will gain new deepwater oil and gas operations from the BG buy, predicts pretax synergies of about $2.5 billion a year and said it expects the acquisition to be "mildly" accretive to earnings per share in 2017 and "strongly" accretive starting a year later. For BG, the deal comes about a month after Helge Lund took the reins as CEO following a one-year management gap.

Portugal's Galp Energia (GLPEF), BG's partner in Brazilian oil fields, was up more than 7% in Lisbon.

In other sectors, shares in EasyJet (EJTTF), a low-cost carrier based at London's Luton Airport, got a slight boost of 0.5% after reporting a 7.5% rise in passengers for the month of March. The increase, from about 5.11 million to 5.49 million passengers last month, raised the load factor to 92.6% compared to 91.5% a year ago.

On the mainland, German stocks fell after a report from the country's Economy Ministry showed that factory orders in Europe's largest economy fell unexpectedly in February, their second monthly decline.

Orders, adjusted for seasonal swings and inflation, declined 0.9% in February after a revised 2.6% drop in January. A 0.2% decline in January eurozone retail trade, released Wednesday by Eurostat, was as expected.

German carmakers led the decline, with Bayerische Motoren Werke shedding 2.17% and Daimler (DDAIF) retreating 1.41%.

In Paris, French buildings material company Cie. de Saint-Gobain (CODGF) added 0.84% after announcing plans to proceed with a controversial deal to buy a controlling stake in Swiss chemicals maker Sika. Sika shares shed 1.04% in Zurich.

Renault (RNSDF) inched up 0.4%. The French finance ministry said it will spend up to €1.232 billion to temporarily boost its stake in the carmaker to block a resolution at the next annual general meeting that could reduce its control over the company.

"This deal shows the state's intention to use all the arms at investors' disposal today to promote a progressive, long-term kind of capitalism," French Economy Minister Emmanuel Macron said in a statement.

Air France-KLM (AFLYY) shareholders paid little attention to Wednesday's strike action by air traffic controllers that forced the carrier to cancel more than 40% of its medium-haul flights. The stock was up 0.15% by late morning.

Later today, after European markets close, all eyes will be on the U.S., with the Federal Reserve due to publish minutes from its last gathering.

Asian stocks were all in positive territory on Wednesday, with the Hang Seng advancing 3.8% to 26,236.66 in Hong Kong, as trading resumed after a five-day break, and the Nikkei climbing 0.76% to 19,789.81.