Petrol prices in Brisbane have soared to the highest prices seen in five months ahead of the Easter long weekend.

Average Australian unleaded prices have soared by 3.5 cents during the past week,  with CommSec senior economist Ryan Felsman blaming a six week rise in global crude oil prices.

However, Mr Felsman says not all hope is lost, claiming petrol prices could retreat in the second half of 2019 as Russia withdrew from its supply-reduction pact with Saudi Arabia, and the United States increased production activity.