12. The CAA or the authorised person concerned shall not detain, or continue to detain, an aircraft on behalf of Eurocontrol under these Regulations by reason of any alleged default in the payment of the charges payable under these Regulations if the operator of the aircraft or any other person claiming an interest therein–
(a)disputes that the charges, or any of them, are due or, if the aircraft is detained under regulation 11(a) of these Regulations, that the charges in question were incurred in respect of that aircraft; and
(b)gives to Eurocontrol, pending the determination of the dispute, sufficient security for the payment of the charges which are alleged to be due.