Morgan Lewis & Bockius has taken the lead role for Deutsche Boerse on its lawsuit against the European Commission (EC) over the rejection of its merger with NYSE Euronext.

The US firm's Frankfurt office has been instructed to advise the German stock exchange following its decision to sue the European Commission at the General Court of the European Union in Luxembourg.

The EC blocked the proposed $7.4bn (£4.7bn) tie-up last month, preventing a deal that would have created the world's largest exchange, arguing it would have given the combined entity a near-monopoly in the market for European derivatives.

Morgan Lewis is fielding a team led by Frankfurt managing partner Christian Zschocke. It is understood that the EC is handling the matter in-house. NYSE Euronext is not party to the legal action.

A spokesperson confirmed: "Deutsche Boerse has taken the decision to appeal against the ruling of the European Commission. In its ruling, the Commission prohibited the planned merger with NYSE Euronext due to antitrust concerns. Deutsche Boerse is of the opinion that several aspects of the ruling are faulty."

The news comes over a year after Linklaters and Wachtell Lipton Rosen & Katz first took roles on the merger negotiations between Deutsche Boerse and NYSE Euronext.

Linklaters' team was led by Duesseldorf-based capital markets partner Ralph Wollburg, who worked alongside Brussels antitrust chief Alec Burnside, who subsequently joined US firm Cadwalader Wickersham & Taft.

The NYSE instructed Wall Street leader Wachtell with corporate partner David Karp in the lead. Cleary Gottlieb Steen & Hamilton advised on EU competition issues with a team led by London-based competition partner Nick Levy alongside Brussels-based competition partner Brian Byrne.