Boris Johnson has confirmed the latest areas to use the eco-friendly New Bus for London vehicles.

The mayor said routes nine and 390 will be the third and fourth buses to make use of the new vehicles, following on from services 24 and 11.

Route nine is run by London United and travels between Hammersmith and Aldwych, while route 390 is Metroline's 24-hour bus that covers numerous destinations in central London, including Notting Hill Gate and Archway, Tottenham Court Road and King's Cross.

The upgraded vehicles will be in operation on both routes by the end of the year and Transport for London's managing director Leon Daniels said 600 of the buses will be rolled out in the coming years.

"By 2016, 20 per cent of buses in the capital will be hybrid and these will be concentrated in central London," he remarked.

Although the government is keen to promote public transport, recent figures released by the Department for Transport showed that bus use fell across the UK in the 12 months to March 2013.