While consumers may be concerned about the potential for price gouging as they fill up in time for the holidays, Kate Lundy from NRMA ACT said she would keep a close eye on bowsers.

"We have been seeing a slow decline in petrol prices in the ACT and there shouldn't be a change in that pattern over the next week," Ms Lundy said.

"There have been incidents of price gouging in the past and the NRMA will be watching to ensure there is responsible behaviour from retailiers."

In the month to April 11, Canberra's average unleaded petrol price fell 9¢ to 1.29¢ a litre. That was 7¢ above the national metropolitan average, but below Sydney's average unleaded price, which rose more than 20¢ in a few days to 134.5¢ a litre.

On average, Canberrans paid more in the past week than those in other major cities, except Hobart (141.1¢ a litre) and Darwin (131¢ a litre). Prices were higher in the capital than in Goulburn (118.9¢ a litre) and Wollongong (125.2¢ a litre), but lower than in Yass (139.2¢ a litre), Cooma (133.8¢ a litre), and Batemans Bay (134¢ a litre).

The upward trend is set to continue into Easter in Sydney and Adelaide. Meanwhile, prices will keep declining in Brisbane, Melbourne and Perth, as well as most of regional NSW.

Ms Lundy said the scrutiny price-comparing smartphone applications placed on retailers should prevent deliberate price hikes over the long weekend.

"Petrol prices in Canberra have been dropping 0.7¢ in the past week, which isn't a dramatic drop, but we should see a similar drop over the next week," she said.

Although Canberrans could be tempted to hold out to the end of the week to hit the pump when it will be slightly cheaper, Ms Lundy advised otherwise.

"To avoid delays motorists should full up a day or two earlier than they leave," she said.

"The same goes to avoid congestion when coming back into town."

The Australian Competition and Consumer Commission said it understood community concern about petrol prices during holiday periods. But as petrol prices were unregulated, it had no power to stop retailers from setting them higher in busy periods.

That's where shopping around comes in handy, an ACCC spokesman said.

"This will help motorists, and also bring more competitive tension to the market," he said.

"Motorists can take advantage of many apps that provide real-time updates on fuel prices to help them source where the best prices are."

With average petrol prices regularly higher in the capital than other major cities, Ms Lundy called for more independent retailers to keep downward pressure on prices.

Spokeswoman for comparison website Compare the Market, Abigail Koch, said discount retailer Costo had slightly helped the situation.

"But as our analysis shows, Canberra has a long way to go before it enjoys the level of petrol competition found in other capital cities," she said.

For now, Canberrans could check ACT Fuel Watch for the cheapest places to fill up.