Sydney petrol prices are set to soar. Source: News Corp Australia

Petrol prices are set to surge towards their biggest jump in close to a quarter of a century.

Latest data shows that a leap in the Singapore refinery gasoline price combined with a rise in domestic wholesale petrol process means NSW drivers look set to pay more at the bowser in coming days.

The rise has already prompted the NRMA to warn its members to fill up their tanks today or tomorrow before the increase begins to bite.

The NRMA said the pump price for unleaded petrol would jump by 17c per litre to $1.50 by Friday.

Figures released by the Australian Institute for Petroleum show that the national average Australian price rose by 3.7 cents per litre, to 142.1c, in the week to 14 June.

In Sydney, the average price of unleaded has risen by 0.8 cents to 142.8 cents per litre

This came as the Singapore gasoline price leapt to a seven-month high, in Australian dollar terms, last week.

Now CommSec is estimating the price of petrol has risen 13.1 per cent so far in the June quarter, with more to come.

This puts the price in line for the largest quarterly increase since the December quarter in 1990.

In a briefing note, CommSec chief economist Craig James said pump prices are set to rise a little further in coming weeks.

Petrol prices are headed back towards $1.50 this week. Picture: Mike Dugdale Source: News Corp Australia

“Motorists are paying on average 30c more per litre for fuel than at the start of 2015, adding an extra $21 to the cost of filling up an average sedan,” Mr James said.

“Petrol is the single biggest weekly purchase for most families.

But Mr James said there is a bright side to the shift in prices.

“The good news for motorists is that petrol prices are still down on a year ago,” he said.

The 13 per cent cent rise so far this quarter comes after a 12.2 per cent fall over the first three months of this year.

The NRMA said regional petrol prices were already starting to rise in most NSW towns.