Provisional attachment of bank accounts permitted with senior customs approval and possible extension, subject to notice and written reasons. Where physical seizure is impracticable, the proper officer may give custody of goods to the owner, beneficial owner, importer or person from whose custody the goods were taken on execution of an undertaking that the goods will not be removed or otherwise dealt with without prior permission; where seizure is impracticable the proper officer may direct such persons not to remove or deal with the goods except with prior permission. The proper officer may, with Principal Commissioner or Commissioner approval, by written order provisionally attach any bank account for a specified period, and the Principal Commissioner or Commissioner may extend that period for reasons recorded in writing and must inform the person concerned.