Bus and rail operator Go-Ahead said the cost of fighting off last year's hostile takeover bid by French consortium C3D had dented profits.

Go-Ahead, the operator of Thames Trains which operate from Brighton to Bedford, said C3D's approach had been "wholly unwarranted" and had landed the Newcastle-based company with a £6 million one-off charge.

The company also owns Brighton and Hove Bus and Coach Company and Gatwick-based handling company GHI. Last week it announced it is taking over a number of bus routes in Crawley after the previous bus company withdrew.

It is also part of the consortium making up Govia, which has won the franchise to take over from Connex South Central. It has pencilled in £1.5 billion worth of improvements for the network, including work to increase capacity on the line from Brighton.

Pre-tax profits for the six months to December 30 were down, falling to £20.1 million from £22 million.

But chairman Professor Sir Frederick Holliday said, while the cost still rankled, Go-Ahead could look to the future with confidence.

He added: "My colleagues and I feel vindicated in our defence of the group's independence as our business strategy unfolds."

Stripping out the one-off charge relating to the C3D bid, pre-tax profits for the period rose 13 per cent to £24.8million, above City expectations.

Operating profits within the company's bus division dipped slightly from £14.9 million to £14.8 million. The figure for its rail operations was up to £9 million from £5.8 million.

Go-Ahead said the bus businesses had performed well in the face of significant cost pressures, including higher oil and insurance charges.

It is planning a series of promotions to attract customers back to its rail services.