1. Member States shall work in close cooperation and provide each other with mutual assistance without undue delay in order to facilitate the implementation, application and enforcement in practice of this Directive and Directive 96/71/EC.

2. The cooperation of the Member States shall in particular consist in replying to reasoned requests for information from competent authorities and in carrying out checks, inspections and investigations with respect to the situations of posting referred to in Article 1(3) of Directive 96/71/EC, including the investigation of any non-compliance or abuse of applicable rules on the posting of workers. Requests for information include information with respect to a possible recovery of an administrative penalty and/or fine, or the notification of a decision imposing such a penalty and/or fine as referred to in Chapter VI.

3. The cooperation of the Member States may also include the sending and service of documents.

4. For the purpose of responding to a request for assistance from competent authorities in another Member State, Member States shall ensure that service providers established in their territory supply their competent authorities with all the information necessary for supervising their activities in compliance with their national laws. Member States shall take appropriate measures in the event of failure to provide such information.

5. In the event of difficulty in meeting a request for information or in carrying out checks, inspections or investigations, the Member State in question shall without delay inform the requesting Member State with a view to finding a solution.