Southern Railway bosses could face huge fines over its "unsatisfactory" and "unreliable" service if it does not fulfil its promises after a grilling from disgruntled MPs.

Representatives from Govia Thameslink Railway, the company responsible for the Southern franchise, and Network Rail are due to face questions from Southern Railway-served MPs on January 18.

Several MPs including Labour's Chuka Umunna, Conservatives Sir Nicholas Soames, Crispin Blunt and Maria Caulfield, and the Green's Caroline Lucas have voiced their criticism Southern's ongoing problems including delayed services, engineering work and not enough carriages or train drivers.

As a result, Rails Minister Claire Perry has invited them to join her next meeting with Network Rail and the train operator at Westminster.

Ms Caulfield, Conservative MP for Lewes who commutes to Westminster, said: "There is a huge cross-party group who are cheesed off.

"For me it is an unreliable, unsatisfactory and expensive service. Residents say to me they are completely fed up. There doesn't seem to be acknowledgement or sympathy from Southern. The conditions are poor, conditions are cramped, people are standing all the way from Lewes. It is not good value for money."

Ms Caulfield, who tweeted it was quicker to get to space by rocket than get home to Lewes by train the day after Tim Peake took six-and-a-half hours to get to the International Space Station in December, added rail fare hikes were "a smack in the face" for commuters.

She said: "We are not talking about 10-minute delays, we are talking about 30 minutes, 40 minutes, sometimes an hour.

"They (GTR) are in breach of contract, penalties could be given. We want them (GTR and Network Rail) both in the same room so they can't just play off against each other. They need to step up and address these problems.

"It affects anyone from the Sussex coast right up to London. And the rail fare hikes are a bit of a smack in the face considering their poor performance. That's why we are more angry. It is adding insult to injury.

"We have been in meetings before and we were promised a new timetable would solve the problems but it hasn't. They have had their chance now and unless they start performing now the penalties will be imposed on them."

On December 17, Streatham MP Chuka Umunna told parliament Southern services were "an appalling joke".

In December Network Rail agreed to set up a £4.1 million reparation fund instead of paying a £2 million fine over the chaos at London Bridge station, which the Office of Rail and Road said would directly benefit GVT services - Thameslink, Southern and Gatwick Express.

GVT is also already working on a remedial plan with the Department of Transport which would see financial sanctions imposed "in extreme cases".

A GVT spokesman apologised for the punctuality of its services and highlighted the "huge" investment of the Thameslink Programme to rebuild London Bridge and benefit passengers in the long term.

A Network Rail spokesman said it was "acutely aware" it needed to deliver more for passengers on one of the "most congested" parts of the railway where "small problems can quickly snowball".

A Department of Transport spokesman said it was aware Southern Railway customers "have not always received the high quality service they deserve", which is why meetings are held regularly.