THE reliability of train services in Sussex will be improved, the transport secretary has promised.

Chris Grayling said he would "step up" work to improve the reliability on routes across the county when pressed by Lewes MP Maria Caufield.

Mrs Caufield said 50 per cent of delays were caused by failing infrastructure.

The promise comes days before members of the RMT walk out on strike over their dispute with Southern Railway over the role of the conductor.

Members of the union have already spent 17 days on the picket line with 11 more dates planned before the end of the year.

Mrs Caufield asked how rail infrastructure is being improved in Sussex during transport questions in the House of Commons this morning.

Mr Grayling told MPs: “We are making a whole range of substantial investments on the rail network in Sussex including longer platforms on the Uckfield line, a new Thamelink depot and upgraded power systems.

“But that said, I want to be clear, I am well aware of the frustration being felt by the passengers in her constituency. One of the key issues, quite apart from the disgraceful and unwarranted industrial action that is taking place at the moment, is that this network is not reliable enough.

“I give assurance to her and her constituents that I am looking very hard at how we step up a programme of incremental improvements that stop these day by day breakdowns that make the current issues much worse.”