Baker & McKenzie has successfully challenged the proposed €5.2bn (£4.3bn) takeover of delivery giant TNT Express by United Parcel Service (UPS), which has collapsed after the European Commission moved to block the deal.

FedEx challenged the merger on competitive grounds after UPS's bid was announced in early 2012, with the European Commission subsequently opening an investigation into the proposed deal in July.

UPS's bid, which was first announced last March, will be officially terminated when Brussels formally blocks the agreement.

Bakers took the lead role for FedEx, with EU and competition head Fiona Carlin and EU competition partner Gavin Bushell, both of whom are based in Brussels, heading up the firm's team.

UPS has been taking advice from Freshfields Bruckhaus Deringer, with the magic circle firm's team including Amsterdam managing partner Winfred Knibbeler, Amsterdam corporate partner Alexander Doorman, Netherlands corporate partner Jan Willem van der Staay and Brussels-based antitrust partner Alan Ryan.

Allen & Overy (A&O) has been advising TNT on the proposed merger with a team led by Amsterdam head of competition Paul Glazener.

In a statement, UPS chairman and CEO Scott Davis said: "We are extremely disappointed with the EC's position. We proposed significant and tangible remedies designed to address the EC's concerns with the transaction.

"The combined company would have been transformative for the logistics industry, bringing meaningful benefits to consumers and customers around the world, while supporting growth in Europe in particular."

The European Commission outlined concerns in October that a potential deal would reduce competitors in the express delivery field from four to three players – UPS, Deutsche-Post's DHL and US-based FedEx.