Northern rail boss tells BBC new timetables need to 'bed in'.
Greater Manchester Mayor Andy Burnham has called for a temporary fare cut on rail routes affected by an interim timetable.
Northern has aborted about 2,000 services since new timetables started on 20 May, with more than 200 cancelled or heavily delayed on Friday.
Northern's managing director David Brown has apologised for the "very poor start" to the reduced timetable, saying: "We've been cancelling far too many trains, inconveniencing far too many people and we're truly sorry for that."