PTT (Cambodia) is able to import drums of 100LL aviation fuel from Thailand for use in Cambodia. Below is the contact for PTT in Cambodia and Thailand. 

PTT Cambodia 
Mr. Pattana Nomjitjiam 
Email: pttcambodia@bigpond.com.kh  
Tel: 855 23 362821-2
Fax: 855 23 213987 

PTT Thailand 
Mr. Chaipruet Watchareecupt
Aviation and Marine Marketing Department 
Email: CHAIPRUET.W@pttplc.com 
Tel: 662 537 2312
Fax: 662 537 2355
Mobile: 661 174 2833

or try chansin.t@pttplc.com