Investigations into how 600 litres of highly flammable aviation fuel leaked onto the road between Queenstown and Wanaka have begun.

Traffic was delayed for four and a half hours this morning after a trailer full of Avgas came loose from the back of a ute.

The container split open, leaking nearly half its load onto the road.

Queenstown Lakes District Council spokeswoman Meaghan Miller says they will be assessing the cost of the clean up next week.

She says why it occurred will be subject to a police investigation and the ute and trailer will be examined on Monday.

Meaghan Miller says the environmental impact is thought to have been minimal.