The levying of a proposed fuel tax does not need further approval from the country's top legislature, a senior official has said amid worries that the levy will add significantly to rising costs.

The Highway Law, revised by the National People's Congress (NPC) in 1999, "has already empowered the State Council to impose the tax at a proper time", the senior official with the State Administration of Taxation told the Shanghai Securities News on Monday.

The remark from the unnamed official has also reportedly fanned speculation that the tax, aimed at encouraging the use of fuel-efficient cars, will be announced as early as Dec 1.