Following a raise of 20% in their off peak train fares, South West Trains has been referred to the Office of Rail Regulation by rail consumer watchdog, Passenger Focus.

SWT state that the increases, due to come into effect on 20 May, are necessary to reduce overcrowding on trains arriving in London before noon. However, the watchdog revealed that the rises were only implemented at stations where SWT had a monopoly.

Anthony Smith, Passenger Focus chief executive told Transport Briefing, "These increases are unacceptable and come only a matter of months after the train operator's last price rises. The affordable, turn-up and go railway has been further eroded and South West Trains is exploiting a monopoly market. Families making day trips to London will be hit hard by these changes."

The increases will affect off-peak trains arriving in London until 12.49.

SWT signed a new franchise last year agreeing to pay the Department for Transport £1.2bn over 10 years. The train operator cannot increase its revenue from season ticket holders because these fares are regulated by the government, however, the contract does allow the company to increase off-peak fares.