The group headquarters of the London Stock Exchange and its German counterpart Deutsche Boerse should be in Frankfurt and not London after the pair have merged, Thomas Schaefer, the finance minister of Hesse, the state in which Frankfurt is located, has claimed.

Deutsche Boerse is the larger company but the combination has been carefully set up as a merger rather than a takeover. The decision to place the headquarters in London was part of that arrangement.

But it is unpopular with German politicians and regulators who fear a loss of influence, and Mr Shaefer has stepped forward to attempt to undo that agreement just weeks before the companies hoped to get regulatory approval to go ahead with the merger.