In the following cases, contracting authorities/entities may award contracts by a negotiated procedure without prior publication of a contract notice and shall justify the use of this procedure in the contract award notice as required in Article 30(3):

(1) for works contracts, supply contracts and service contracts:

(a) when no tenders or no suitable tenders or no applications have been submitted in response to a restricted procedure, a negotiated procedure with prior publication of a contract notice or a competitive dialogue, provided that the initial conditions of the contract are not substantially altered and on condition that a report is sent to the Commission, if it so requests;

(b) in the event of irregular tenders or the submission of tenders which are unacceptable under national provisions compatible with Articles 5, 19, 21 to 24 and Chapter VII of Title II, in response to a restricted procedure, a negotiated procedure with publication or a competitive dialogue, insofar as: