Toyota's Prius was the best seller in the April-September period (first fiscal half year) in Japan, becoming the first hybrid to top the sales charts for the six-month period, industry groups said on Tuesday.

Sales of the petrol-electric car more than tripled year on year to 116,298 units thanks to government tax breaks for the purchase of fuel-efficient vehicles, according to data released by the Japan Automobile Dealers Association and the Japan Mini Vehicles Association.

The car is expected to become the top seller for the whole of fiscal 2009 ending next March as the order backlog is well over 100,000 units, industry sources told Kyodo News.

The Prius has become more affordable because the minimum price of the new model launched in May was about JPY280,000 lower than its predecessor at JPY2.05m and its fuel economy is 7% better at 38 kilometres per litre of fuel.

Honda's rival Insight hybrid, launched in February, ranked sixth with sales of 55,845 vehicles.

In total fiscal first half sales including minicars (engines up to 660cc) Suzuki's WagonR minicar was second with 93,193 units, followed by Daihatsu's Move with 84,529 units.

The Prius also topped the sales charts in September, selling 31,758 units followed by the WagonR (18,282), and Honda's Fit (aka Jazz; 17,241 units).