CommSec economist Savanth Sebastian yesterday said the national rise was the largest increase at the start of a calendar year in nine years.

He blamed a weak Australian dollar for pushing up the costs of imported fuel and the refined fuel barrel price out of Singapore, sitting at a four-month high of $US119.20 a barrel.

Mr Sebastian said the 14 barrel price surge since November would be com Leg 1?pounded by a likely 2 rise in the next fortnight.

According to the Australian Institute of Petroleum, the national petrol price rose from 153.4 a litre from December 8 to 158.1 on January 5.

Tasmanian price rises were less dramatic at 161.5 to 162.3 over the same time, but was still 4.2 above the national average.

RACT spokesman Vince  Leg 2?Taskunas agreed that the Singaporean barrel price and worsening exchange rate would put upward pressure on petrol prices, but said Tasmanians could be spared from further price rises.

``Tasmanian retail prices, already being very high comparatively, should absorb the 2 rise predicted by the CommSec analyst,'' he said.

Launceston petrol prices 10 months ago were averaged at 158 a litre on April 7.

This dropped further to a bit above 152 a litre on May 12.

The May 12 price was price sustained over three weeks,  Leg 3?but skyrocketed between July 7 and 21 by more than 10  to an annual high of just above 164 a litre.

The Australian Competition and Consumer Commission last year raised concerns over fuel savings offered through shopper dockets from Coles and Woolworths had decreased competition in fuel retail sale.

The major supermarkets agreed to cap discounts at 4 a litre, effective from this year.

The supermarkets had previously offered discounts of up to 8 a litre.