16. (1) If the master of any ship in respect of which any light-dues are payable at any port causes the ship to leave such port without having paid the same, the Collector of customs at that port may be writing require the Collector of customs at any other port in Bangladesh to which the ship may proceed or in which she may be to recover the dues remaining unpaid. (2) Any Collector of Customs to whom such a requisition is directed shall proceed to levy such sum as if it were payable under this Act at the port at which he is the Collector of customs, and a certificate by the Collector of customs at the port at which the light-dues first became payable, stating the amount payable, shall be sufficient proof in any proceeding under section 13 or section 15 that such amount is payable.