LONDON (REUTERS) - Deutsche Boerse and the London Stock Exchange Group have submitted their US$29 billion merger deal to European Union competition regulators ahead of a Sept. 28 deadline for a preliminary review.

The deal, which will create the world's biggest exchange by revenue, is likely to face tough scrutiny because of the huge combined presence of the two companies in derivatives clearing.

The European Commission's antitrust department, whose approval is needed for the deal to proceed, has set a provisional deadline of Sept. 28 for its preliminary review.

"We believe the merger will create significant value for our customers and shareholders, and facilitate economic growth through the creation of a global markets infrastructure group, anchored in Europe," the exchanges said on Thursday.

The LSE's LCH.Clearnet is Europe's main clearing house for euro-denominated swaps and that could be a concern for the EU competition enforcer. Analysts say the exchanges may have to offer major concessions such as selling overlapping businesses.

The exchanges expect the EU scrutiny to broaden into a full investigation of about five months. Belgium, Portugal and the Netherlands, trading locations of rival exchange Euronext , have already expressed concerns about the deal.

Deutsche Boerse and LSE are expected to argue their combined firm will be better able to compete with United States and Asian rivals.

US and Russian authorities have already approved the deal which also needs a green light from the German state of Hesse.