
The European Commission is investigating the proposed £11.6bn takeover of Scottish Power by the Spanish firm Iberdrola.
The preliminary inquiry follows Scottish National Party accusations that Iberdrola's expansion was being subsidised by tax-breaks in Spain.
The commission will consider incentives offered by the Madrid government.
It will then decide on 16 February whether to let the deal go ahead or to carry out a more detailed inquiry.
Iberdrola said it was co-operating with the commission and remained "confident" its plan to takeover Scottish Power will not face competition hurdles.
It has said it plans to retain Scottish Power's offices in the UK, where the company employs about 9,500 people.