Simon Hughes wants to make the charge more user-friendly

The Lib Dem MP has outlined his plans for the �5 central London road toll which operates between 7am and 6.30pm.

He would also offer drivers five free journeys a year within the zone and let people who pay the charge every day 'block buy' tickets in advance.

Current mayor Ken Livingstone said it was a bad idea because traffic would rise as people were trying to get home.

Mr Hughes added he would oppose the scheme being extended west to include parts of Kensington and Chelsea.

The system is working well and we might make some small variations but they will only be small Mayor Ken Livingstone

He will also make trips into the zone free between Christmas and New Year.

The congestion charge scheme was introduced last February by Mr Livingstone.

Journey times and traffic levels have decreased but the system has been criticised by some businesses which claim it has hit trade.

Speaking to BBC London, Mr Hughes said: "It is very noticeable that Oxford Street businesses and others have said they are not against the congestion charge in principle.

Business advantage

"It has reduced congestion and pollution.

"But they want something to take the pressure off and we need to give some little advantage to the business community."

But Mr Livingstone told BBC London: "One of the options has always been to bring the time down to 6pm, especially if we expand westward, to let people drive to the theatre for example.

"Trouble is, just when people want to get home is not when you want the city seized up again.

"I've noticed that at about 6.30 the city does become a bit sticky.

Split community

"The system is working well and we might make some small variations but they will only be small."

Conservative mayoral candidate Steven Norris will outline his plans for the congestion charge at Fulham Town Hall on Monday.

In a statement he said he will oppose the westward extension: "Livingstone's extension plan will be bad for business and residents alike.

"The proposal will also split the community in half so that those on the wrong side of the road will soon have to pay �5 to take their kids to school, drive to work or get to the local shops."

Green plans

Green Party candidate Darren Johnson has said he would expand the scheme across London, with a central, inner and outer London zone.

The charges for larger engine vehicles would be �10 in central London, �5 in Inner London and �4 in Outer London, with a discount for smaller engine vehicles.

The charges for lorries would be increased to �15 for central London, �10 for Inner London and �5 for Outer London.

Motorbikes would pay �2.50 for central London, but nothing in the other zones.

UK Independence Party mayoral candidate Frank Maloney has vowed to scrap the congestion charge, open up more one-way streets to ease traffic flow and create a 24 hour public transport service.

The London mayoral elections take place on 10 June.