BUSES running through Bexley will have to prove their green credentials in a move by Mayor of London Ken Livingstone.

Mr Livingstone's transport strategy makes a commitment to improving environmentally-friendly forms of transport.

Now bus companies which are not part of London Buses will have to apply for a London Service Permit to operate in the Greater London area.

Previously a local licence was issued.

This will apply to services such as tourist, commuter runs, private school and special event buses.

One main feature of the new rules is to ensure vehicles comply with European standards on exhaust emissions, with a commitment to reduce them further.

Other conditions include measures to improve passenger safety and convenience especially for those with impaired mobility.

Announcing the change Mr Livingstone said: "I am committed to improving air quality and reducing health impacts of traffic."

Operators which applied for a licence before July 2000 can continue with them until they expire.

Hi-tech smart cards could be introduced on London Buses and the Tube by the end of the year.

The £1bn scheme, likely to be phased in gradually, will use special sensor pads which reads cards at ticket gates and barriers.

It will replace the current paper ticket Travelcard system.