A bus driver and two other people were left in a critical condition after a new Routemaster collided with a queue of stationary traffic.

The 12-tonne vehicle was travelling along Chelsea Bridge Road and caused a six-vehicle pile-up at the junction with Ebury Bridge Road, Pimlico, at about 1pm on Sunday.

Two other buses and three cars were involved in the incident, which left 12 people with minor injuries.

Transport for London said the bus was in service but 'off route' at the time of the crash.

It is unclear why the number 11 was not on its normal route.

Ten ambulances treated passengers at the scene and London Fire Brigade used hydraulic cutting equipment to free at least one person from the wreckage.

The 58-year-old bus driver was seriously injured, along with a 47-year-old man and 34-year-old woman, who were in a Citroen car left in a crumpled heap.

Their injuries are not thought to be life threatening.

Mike Weston, operations director for London Buses, said: "We can confirm one of these buses was a New Bus for London vehicle.

"Our first concern is, of course, for the driver, passengers and others involved in this incident and can confirm the emergency services were in attendance.

"There will be a thorough investigation into this incident as a matter of urgency."

TfL and the Met Police are investigating. The Met Police did not arrest anyone but are appealing for witnesses to the crash.

A police spokesman said: "At this early stage it appears the driver of a New Bus for London collided with a line of stationary traffic from the rear. Enquiries continue to establish the circumstances of the incident."

Officers from the Met's Traffic Unit want anyone who witnessed the incident, or the events leading up to it, to call them on 020 8285 1574.

* Picture by John Pannell