Talks are being held between rail bosses and politicians over disruption to Sussex train services as a result of the upgrade to London Bridge station.
Rail minister Claire Perry has called a meeting with the managers of Southern, Thameslink and Network Rail. All three have apologised for the problems.
The Department for Transport (DfT) said it was so officials, the rail watchdog and MPs could discuss improvements.
The private meeting is being held later at the House of Commons.
London Bridge station is being rebuilt as part of the £6.5bn Thameslink programme.
But commuters across the South East have reported delays and overcrowding.
A spokeswoman for Southern said the rail operator was working with Network Rail to improve performance.
She said some changes had already been made to improve punctuality and had proved to be beneficial.
Last month, Network Rail apologised for delays.
Simon Blanchflower, Thameslink programme director, said Network Rail recognised the service around London Bridge had not been good enough and the company was doing everything it could to tackle the problems.
Thameslink also apologised and said timetable and station layout changes had been made to alleviate the problems.