7. Administrative expenses
 
  2018
US$’000		   2017
US$’000		  
Directors’ and staff costs        
Non-executive directors 612   536  
Employees: salaries 15 459   9 213  
                           bonuses 3 262   1 339  
                           pension fund, medical aid and other contributions 1 707   1 405  
  21 040   12 493  
Audit – external audit services 490   429  
Audit – other services* 90   –  
Consulting 2 611   2 773  
Corporate and social investment 157   73  
Depreciation 850   453  
Discount facility and related fees 701   516  
Equity-settled share-based payment expense 4 019   4 342  
Internal audit 206   –  
Listing fees and investor relations 461   260  
Health and safety 1 019   300  
Impairment and write off of property, plant and equipment 267   –  
Insurance 697   914  
Legal and professional 634   873  
Loss on disposal of property, plant and equipment 37   196  
Office administration, rent and utilities 1 296   660  
Security 1 776   828  
Telecommunications and IT related 1 374   719  
Training 504   313  
Travelling and accommodation 410   358  
Sundry 593   403  
  39 232   26 903  

* Other services paid to the former external auditor relates to tax and accounting services as approved by the Audit Committee.

  2018   2017  
Number of employees 1 758   701