Motorists are getting an early Christmas present, with the national price of petrol falling below $1.90 a litre for the first time since February.

On Tuesday morning, Z Energy led a price cut at its company-owned sites, taking 2c off the price of 91 octane petrol, to $1.899 a litre.

Petrol has fallen below $1.90 for the first time since February. Photo: File.

According to figures compiled by the Automobile Association, it's the first time that the national price has fallen below $1.90 a litre since February 16.

'While the exchange rate has firmed a bit this is simply passing on the decreasing international fuel prices, which have been trending down,” says a spokesman for Z Energy, adding that the drop came ahead of the busiest driving period of the year.

The most common type of premium petrol, 95 octane, is now below $2 a litre, with Z stations charging $1.989.

The national price generally refers to company-owned sites of the major retailers, with discounting in some parts of the country meaning many motorists pay less, while in remote parts of the country, the pump price can be higher.

Tuesday's fall is the second drop in less than a week, with BP believed to have led a 2c a litre drop on December 4.

The latest falls come as the international price of oil fell to a seven-year low, after the Organisation of the Petroleum Exporting Countries (OPEC) failed to reach an agreement on how much oil its members should produce.

West Texas Intermediate, the US benchmark crude, fell 5.8 per cent to US$37.65 a barrel, the lowest level since early 2009. Brent crude, the international benchmark, also fell, down 2.5 per cent to around US$42 a barrel.

Throughout 2015 members of OPEC have been continuing to keep production of crude oil high in a bid to squeeze out new producers, mainly in the United States, resulting in a global oversupply and plunging prices.

Since reaching the highest level of the year in June, at $2.119 a litre, the pump price in most locations has fallen by more than 10 per cent since.