A controversial motorway bus lane scheme backed by deputy Prime Minister John Prescott, but opposed by motoring organisations is to stay.

The green light for the 1.9m pilot scheme on the M4 west of London came after a Transport Research Laboratory report showed the lane was improving rush-hour journey times for both buses and cars.

But during off-peak periods, journey times for buses and cars have increased by only one minute.

Huge queues built up on the M4 after Mr Prescott opened the lane in June, 1999. Later, there were reports that a car carrying Tony Blair had cheated and used the lane after getting stuck in traffic.

The report on the 3.5-mile lane's first year in operation said that on average, each bus saved 3.5 minutes and each car one minute during peak times.

The AA remained unconvinced, saying the bus lane could be hailed a success only if significant numbers of drivers switched from cars to public transport.