Almost half of new cars sold in Norway in the first six months of 2019 were powered by fully electric engines, up from just over one-quarter in the same period last year, ensuring the Nordic nation retains its top global ranking in electric vehicle sales.

Tesla's Model 3 was Norway's top-selling vehicle, the Norwegian Road Federation said when announcing the latest sales data on Monday.

In total, 48.4 percent of all new cars sold from January to June were electric, surpassing the 31.2 percent seen for the full year 2018, and making oil-producing Norway the global leader in per-capita electric car sales by a wide margin.

Seeking to end the sale of internal-combustion engines by the middle of the next decade, Norway exempts battery-driven cars from the heavy taxes imposed on vehicles powered by fossil fuel. It also offers benefits such as discounts on road tolls.

The policy has boosted brands such as Tesla, Nissan, Hyundai and BMW, which all offer fully electric vehicles, rather than hybrids that use electric motors to drive the car but also have a combustion engine.

Brands without fully electric offerings, such as Ford and Daimler's Mercedes-Benz, have seen sales drop, although Ford and Mercedes are among several automakers that have promised to offer electric cars in Norway from 2020.

Tesla sold 3,760 vehicles in Norway in June, for a 24.5 percent share of all cars.

Most of its sales were of the mid-sized Model 3, while the bigger Model S and Model X have seen lower year-on-year volumes.

The International Energy Agency, which includes the more widely sold plug-in hybrids when counting electric cars, measured Norway's share at 39 percent of sales in 2017, far ahead of second-place Iceland at 12 percent and Sweden at 6 percent.