Southern dispute is transport secretary's 'top priority'
New Transport Secretary Chris Grayling has said resolving the Southern trains dispute is "top of his priority list".
Passengers have suffered months of delays, cancellations and a reduced timetable due to staff shortages and strike action by conductors.
Asked if he would remove the rail franchise, he said he would look "very carefully at what the position is".
Mr Grayling warned: "This has got to improve quickly".
Southern and the RMT union are in dispute about plans for drivers, rather than guards, to open and close carriage doors.
'This needs to be sorted'
Mr Grayling told BBC Radio 4's The World This Weekend he had been in the job 36 hours and had already had meetings about Southern.
He said he would hold further meetings on Monday.
"This is right at the top of my agenda. This needs to be sorted," he added.
Southern is one of four railways operated jointly under a government management contract by Govia Thameslink (GTR).
Last Monday, Southern axed 341 of its 2,242 weekday trains to try to provide a more reliable, temporary timetable.
Fifteen services have since been reinstated, including five serving Mr Grayling's Surrey constituency of Epsom and Ewell.
GTR insisted the trains were chosen before his appointment.
David Hodge, the leader of Surrey County Council and a Southern commuter, said he understood the anger of passengers and businesses and urged all sides to "put their heads together" for a solution.