London Stock Exchange Group's proposed merger with Deutsche Boerse will be blocked by European Commission (EC) antitrust regulators, according to reports on Wednesday.

A veto will be published within a matter of days, multiple sources told Reuters, scuppering plans to create Europe's biggest exchange. LSE, Deutsche Boerse and the EC all declined to comment.

If accurate, the EC's rejection comes twelve months after the UK and German bourses first announced plans to create powerhouse of trading in stocks, bonds and derivatives and post-trade services.

Britain’s vote to leave the European Union in June added complexity and threatened the tie-up early on. 

Deutsche Boerse chairman Joachim Faber recently put the blame for the failed merger on Brexit.

There were also growing calls from German politicians that the headquarters be moved from London to Frankfurt because of Brexit - a concession most LSE executives did not wish to make.

More crucially, a demand from regulators that the LSE sell its Italian electronic-trading platform for bond and repo markets, MTS, was publicly ruled out by the UK exchange last month.

The refusal effectively derailed the €29 billion ($31 billion) deal.

Analysts at Jefferies said the merger was in the “ninth inning of collapse” this week.

They also dismissed the possibility of other cross-border stock exchange mergers in the near-term due to complex regulatory frameworks and nationalistic views. 

The latest and seemingly unsuccessfully attempt is the third time the LSE and Deutsche Börse have tried to strike a deal, first in 2000 then in 2005.

The EU also blocked a $17 billion tie-up between what was then NYSE Euronext and Deutsche Boerse in 2012.