BUS passengers have been warned to expect "inevitable" fare increases as a city bus company struggles to cope with a 70 per cent increase in its fuel bill.

Louisa Weeks, the operations manager of the Oxford Bus Company, said that current fuel costs were more unstable than at any time in the last 40 years.

Ms Weeks said: "Over the last 12 months the price we pay for fuel has risen by over 71 per cent.

"We have colleagues that have been in the industry for over 40 years and they cannot remember a time when prices were so unstable - not even during the Suez Crisis in 1956 or the fuel crisis in the 1970s.

"We are doing our best to run as economically as possible and keep our costs down as much as we can, but it is inevitable that fares will have to rise at some point."

The Oxford Bus Company buys 110,000 litres of diesel a week to power its fleet of 148 buses.

Fuel is its second largest cost after staff.

It has suffered a larger percentage increase in the cost of fuel than car owners because the company receives tax rebates from the Government as part of a campaign to encourage the use of public transport.

The company last increased fares in September last year, with some return fare tickets going up by 20p - a ten per cent rise.

Ms Weeks said the company usually only increased fares once a year, adding: "We would like to maintain the 12-month gap between increases.

"But every day as fuel prices go up and up, that looks more unlikely and we may have to bring a fare increase forward."

Noam Bleicher, of the Oxford branch of Bus Users UK, said: "It is very unfortunate. We would sooner that prices remained stable or went down, as would everybody.

"We would like Oxford Bus Company to hold off a price rise as long as possible, but we appreciate the position it is in. We would rather they put prices up than cut services."

Mr Bleicher claimed, however, that Oxfordshire motorists would not be driven back into their cars by the bus price increases because they were suffering larger increases in their fuel bills than the comparative rise in bus fares.

The Oxford Bus Company admitted that the number of people travelling on its buses had increased in the last couple of months.

But it said it could not be sure whether this was down to an increase in motorists' fuel costs.

It is not only bus operators who are struggling to absorb the rising costs of fuel.

Alan Woodward, secretary of the Oxford Licensed Taxi Cab Association, said drivers had seen diesel prices increase by roughly 15 to 20 per cent since the last taxi fare rise in February.

He said: "We are struggling because we cannot put two or three applications to the city council in a year for fare increases.

"It is serious. I am getting complaints from drivers every week about what we are going to do about the fares."