ThisIsMoney.co.uk said:A RAIL company is facing an investigation for restricting cheap day return tickets to London.
First Capital Connect is the subject of an official complaint by the London passenger watchdog.
The firm upset travellers when it banned use of the return half of cheap tickets on the former Thameslink and Great Northern routes at the peak evening period.
It means passengers now have to buy the far more expensive standard tickets if they intend to return between 4.30pm and 7pm.
Passengers used to buy cheapday return tickets after the morning peak - at a discount of between 33 and 50% - which allowed them to return at any time.
Today London TravelWatch, the official passenger watchdog, wrote to the rail regulator demanding action. Its chief executive Rufus Barnes claimed First Capital Connect had earlier said the restrictions were to ease overcrowding - only to reveal later that the aim was also to increase revenue.
In the letter he wrote: 'More recently FCC has acknowledged that another reason for the restrictionis to increase revenue to pay the massive £800 million-plus premium to which they committed over the full life of the franchise.'
He said there was also 'concern' over whether there had been 'unreasonable and anti-competitive collusion' between First Capital Connect - owned by First Group - and rival rail operators GNER and Midland Mainline, which had also applied restrictions.
The move comes as pressure mounted on First Group's other London franchise, First Great Western, which operates from Paddington. The rail regulator has ordered the operator to improve its dismal punctuality record.
First Great Western was the worstperforming long-distance rail firm in the year to March, with only 78.6% of its trains arriving on time. It was the only long-distance operator with a worse punctuality record than the previous year. A spokesman for the regulator said: 'We have been looking at its performance closely since the spring. It continues to disappoint.'
A spokeswoman for First Capital Connect said the change to the cheap day return was made to 'spread demand away from crowded peak trains onto less busy trains before and after the peak.'
First Group saw profits increase 6.5% to £176m for the year ending in March.