UK's Southern rail strike next week cut short but union adds more dates

(Adds updated ASLEF statement)

LONDON, Jan 4 (Reuters) - Train drivers on Britain's Southern rail commuter network have cut a planned six-day strike on one of London's main commuter networks next week but added more stoppages later in January.

Strikes next week will now take place on Jan. 10, 11 and 13 after the ASLEF union reduced a walkout due to last from January 9 to 14, the latest action in a dispute over whose role it should be to open and close train doors.

ASLEF said on Wednesday it had added new strike dates for Jan. 24, 25 and 27, in a move which it said reflected the "longer-term view" it was taking of the dispute.

Southern train services connect Brighton and Gatwick Airport to London, and are run by GTR, a joint venture owned by London-listed Go-Ahead and France's Keolis.

The network has been hit by months of industrial action, with stoppages by ASLEF and the RMT, which represents conductors, causing Britain's worst rail disruption for two decades.

"ASLEF's move shows pure contempt for the travelling public and it still causes massive disruption over next week," a Southern spokesman said. "These strikes are pointless and they should call the whole thing off and let common sense prevail."

But ASLEF general secretary Mick Whelan called on the company to reach a settlement.

"It is time for the company to come up with a genuine offer rather than carry on posturing," he said in an emailed statement.

(Reporting by Sarah Young; editing by Stephen Addison)