Tunis has experienced long lines of cars over recent days with people waiting to fill their tanks. Critics see it as another sign of an unfolding crisis in public finances.
The petrol tanker now unloading at Bizerte will give Tunisia an extra few days of supply, taking it to 10-14 days in total, down from the usual 60 days of strategic reserves, said Salouan Smiri, a senior official in the oil section of the UGTT union.
Tunisia is already facing shortages of some subsidized goods, with empty supermarket shelves causing protests last month, as it seeks an international bailout to finance debt repayments and state spending.
"The shortage of fuel supply may resume if the state does not find enough liquidity to pay for upcoming loads," Smiri said on Shems FM radio.
The government has repeatedly denied that it is struggling to pay importers for goods — such as petrol, flour and sugar — that it sells at a subsidized rate, and has previously blamed shortages on internal speculators.
However, while Energy Minister Naila Nouira blamed the shortage on consumer behavior and global distribution issues, she also appeared to acknowledge that payments to importers were contributing to the problem.
"The reason for the scarcity of fuel is the rush of people... many Tunisians are taking more than they need," she said on Mosaique FM radio.
"There is financial pressure due to the immediate pace of payment that vendors are asking," she added.
Last week the ratings agency Moody's said Tunisia faced large fiscal and external imbalances, and elevating financing risks, representing significant credit weakness.
The government hopes soon to finalize a staff-level agreement with the International Monetary Fund (IMF) for a rescue program involving potentially unpopular reforms that could unlock further bilateral budget support.