Hong Kong saw its first electric taxis hit the streets on Saturday in a step towards reducing the city's high levels of roadside pollution.

The 45 bright red cars were launched by Chinese electric vehicle producer BYD, which is partly backed by US investment titan Warren Buffett.

Called the BYD e6, the five-door crossover sedans are powered by iron phosphate batteries and take two hours to charge, a statement from BYD said, adding that they can then travel for 300 kilometres (more than 180 miles).

The cars have been rented by the Hong Kong Taxi and Public Light Bus Association, which is testing them over the next six months.

"The idea of being environmentally friendly is a global trend and the electric car is one good example," said Wong Chung Keung, president and chairman of the association.

"An electric car saves the cost of fuel and will allow our taxi drivers to earn more," he added, saying that a normal taxi would cost HK$0.8 (10 US cents) to run per kilometre (0.6 miles) while an electric car would cost HK$0.2-HK$0.3.

He called for more charging stations around the city to encourage taxi drivers to go electric -- BYD said it is setting up 47 chargers in nine charging locations near car parks.

Hong Kong's Financial Secretary John Tsang was quoted in a BYD statement as welcoming the electric car and saying he was committed to "promoting environmental sustainability by laying the foundation for Hong Kong to become a zero emissions city".

The government announced revisions to its air quality objectives for the first time in 25 years in January 2012, after University of Hong Kong research showed pollution-related illnesses killed more than 3,000 residents a year.