(Adds PM comments, background, share price)
By Sarah Young
LONDON, Dec 14 (Reuters) - British Prime Minister TheresaMay condemned as "appalling" a rail strike that left hundreds ofthousands of London commuters facing a second day of travelchaos on Wednesday.
Speaking in parliament, she urged the two sides to find asolution to avoid prolonging Britain's worst rail disruption fortwo decades.
Passengers trying to get to London from the southeaststruggled to get to work as drivers on Southern Rail - part ofthe country's biggest rail franchise - continued a 48-hourstoppage over a dispute about whose job it should be to open andclose the train doors.
May called for an end to the action as Southern and thedrivers' union Aslef met for talks at the conciliation serviceAcas before more stoppages planned for Friday and in January.
"This is an appalling strike," she said. "We've seendriver-only operated trains on rail networks in the UK fordecades. I hope that the talks at Acas are going to lead to anend to this strike."
"There is only one body responsible for the current strike,that is Aslef," she added.
Wednesday's talks have not yet involved the other main railunion, the RMT, which represents conductors, and is alsoinvolved in the dispute. It is planning strikes on the Southernnetwork next week.
Southern, run by Govia Thameslink Railway (GTR), a jointventure owned by London-listed Go-Ahead and France'sKeolis, told passengers not to try to travel during the strike.
Commentators said this week's strikes would have the biggestimpact since action by signal workers in the mid-1990s.
They follow a series of stoppages on Southern this yearwhich have caused misery for commuters. Some of them say theyhave even lost their jobs because they could not get to work ontime.
Southern said in a statement it hoped the talks with Aslefwould be productive, and added that it had asked to speak to theRMT at Acas later on Wednesday, to try to end the dispute.
Parent company Go-Ahead, which has apologised for thetroubles on Southern, is due to provide investors with a tradingupdate on Thursday.
The strike action on Southern is not a major concern forGo-Ahead investors due to the terms of the contract between therail operator and the government which mean the latter must takethe hit for revenues lost to strike action.
(Additional reporting by Michael Holden, editing by StephenAddison)