The European Commission, which opened a full-scale investigation into the deal in July, will send a statement of objections or charge sheet setting out its concerns about specific areas, the person said, though it is possible the timetable for doing so could slip to next week.

The EU competition enforcer had previously flagged worries about reduced competition in the supply of some types of trains and signalling systems and higher prices as a result of the companies' plan to merge their rail operations.

It also said the combined company would be three times as big as its closest rival, while new players are unlikely to emerge to challenge Siemens and Alstom.

The Commission declined to comment.

German industrial group Siemens and French rival Alstom announced the planned rail merger in September last year, backed by French President Emmanuel Macron but criticised by opposition politicians amidst fears of French loss of control of the TGV high-speed train.

Siemens makes ICE high-speed trains.

(Reporting by Foo Yun Chee; Editing by Adrian Croft)

By Foo Yun Chee