1. The competent authority shall be given all supervisory and investigatory powers that are necessary for the exercise of its functions. It shall exercise such powers:
(a) directly; or
(b) in collaboration with other authorities or with the market undertakings; or
(c) under its responsibility by delegation to such authorities or to the market undertakings; or
(d) by application to the competent judicial authorities.
2. Without prejudice to Article 6(7), the powers referred to in paragraph 1 of this Article shall be exercised in conformity with national law and shall include at least the right to:
(a) have access to any document in any form whatsoever, and to receive a copy of it;
(b) demand information from any person, including those who are successively involved in the transmission of orders or conduct of the operations concerned, as well as their principals, and if necessary, to summon and hear any such person;
(c) carry out on-site inspections;
(d) require existing telephone a