The company, whose rail unit operates the 1.1-billion-pound franchise which runs into central London from Wales and the west of England, is looking at activating a break clause in the contract allowing it to terminate the franchise in 2013, the report said.

The Observer said the move would save the bus and rail operator 826.6 million pounds in payments to Britain's government over the next three years.

FirstGroup has been hit by delays in the introduction of a new generation of intercity trains. A modern fleet of trains would have helped generate enough revenue to cover an escalation in fees from 2013 to 2016.

Earlier this month the government said the new intercity trains would arrive from 2016, not 2013 as initially planned.

FirstGroup was not immediately available for comment.