Iran's government plans to ask parliament for an extra $7 billion budget to cover the growing price of fuel imports, it was reported, even after the major oil producer began petrol rationing last year.

Oil Minister Gholamhossein Nozari said the sum was needed to import petrol during the Iranian year that ends on March 20, the Farhang-e Ashti daily reported.

In February the parliament authorised the oil ministry to import petrol and gas oil for the equivalent of $3.2bn in the fiscal year that started on March 21.

'Nozari said we will need $6.5bn to $7bn for the import of fuel in the second half of the year,' Ali Adianirad, spokesman for parliament's Energy Commission, reported the minister as telling lawmakers.

'The minister said extra budget was needed because of the higher price of petrol and gas oil in the world market,' the newspaper quoted the spokesman as saying.

Under the rationing scheme, fuel has been sold at the heavily subsidised price of 1,000 Iranian rials (11 US cents) a litre. The government revised the system, starting from March, to let drivers buy fuel above their 120-litre-a-month quota at 4,000 rials a litre.

Officials had previously said both consumption and imports dropped after Iran launched the rationing to curb consumption, which had soared well beyond its ability to refine crude.

Despite being the world's fourth largest oil producer, Iran depends on expensive imports as it lacks the refining capacity to meet domestic demand in full. Petrol imports are a sensitive issue for Tehran. The US sees the imports as a potential weakness.