'1. The Commission may invoke the procedure provided for in paragraphs 2 to 5 when, prior to a contract being concluded, it considers that a serious infringement of Community law in the field of procurement has been committed during a contract award procedure falling within the scope of Directive 2004/17/EC or Directive [on Concessions], or in relation to Article 27(a) of Directive 2004/17/EC in the case of contracting entities to which that provision applies'.