BUS passengers will tomorrow be hit with fare hikes as one of Scotland's largest bus and coach operators increases ticket prices by almost twice the rate of inflation.

Stagecoach, whose founder and chief executive is multi-millionaire SNP donor Sir Brian Souter, is raising fares by an average of 5% for bus journeys in its west of Scotland and Highlands divisions.

Meanwhile, passengers using the Aberdeenshire-based Bluebird service will see ticket prices increased by 4.1%.

Fare rises have already hit Stagecoach services in the East Scotland division, with a 5% increase on March 25, against 2.8% inflation.

The fare review will also affect passengers on Scottish Citylink services, 35% owned by Stagecoach. Standard fares on its intercity routes, such as Glasgow to Edinburgh, will increase by 4% from Easter Monday, pushing a standard single fare from £6.80 to £7.10.

Stagecoach, last year rated the cheapest bus company in Britain for weekly travel by independent transport consultant TAS, said it had been forced to increase fares due to the pressures of rising fuel costs and the cap in Scottish Government compensation to bus operators to maintain free travel for over-60s.

Edward Hodgson, managing director of Stagecoach West Scotland said: "We understand this will be frustrating for our passengers, but we have done our best to keep fare changes to a minimum. We are facing continued rising costs in a number of areas of our business and we are seeing reduced public-sector support for bus services as local authority budgets continue to be squeezed."

A spokesman said the company would freeze the majority of other fares, including First Day and return tickets.

Ronnie Park, managing director of First Glasgow, said the operator expected an increased demand for bus travel in the city as Glasgow City Council prepares to implement a 25% increase in on-street parking charges from Monday. The change will force motorists to pay £3 instead of £2.40 to park in the city centre for one hour.

Mr Park added: "Almost every cost associated with running a bus company is increasing. A recent study by the Confederation of Passenger Transport showed overall operating costs for bus companies increased by 4.7% in 2012. Those costs are likely to increase in 2013. However, we have done everything possible to avoid passing those costs on to our customers."

Tom Hart, vice-president of the Scottish Association for Public Transport, said the only way to prevent further increases was to reform the concessionary travel scheme.

A Transport Scotland spokeswoman said: "Our priority is to do what we can to deliver bus travel that is affordable and attractive to the public. Currently, we provide some £250m annually to support a range of schemes including Bus Service Operators Grant, Concessionary Travel and the Scottish Green Bus Fund.

"This continued support is in stark contrast to the UK Government.

"We have all suffered brutal Westminster budget cuts, but this Scottish Government remains committed to maintaining our track record in funding bus travel."