The substance would now be sent for forensic analysis to determine exactly what it was, Mr Petherick said.
He praised the officers' instincts in searching the vehicle.
"(It) is something not so easily taught in the classroom, it's seeing something and recognising it doesn't look right and then doing something about it which is what these two officers did this morning."
KHAT:
• Khat (pronounced "cot", also known as qat, qhat, catha and mirra), is native to Africa and southern Arabia;
• It is an evergreen shrub or tree that grows to about four metres tall;
• It has oval, serrated leaves between eight and 10 centimetres long and small, five-petalled, white flowers;
• The young leaves (preferred part) and buds are reddish green while the fruit is an oblong three-angled capsule containing one to three winged seeds;
• The plant has been found previously in private and public gardens here with owners not aware of any issues associated with it;
• Khat contains two psychoactive substances, cathine and cathinone; and
• Both cathine and cathinone are Class B controlled drugs