Southern Railway and Thameslink operator Go-Ahead has said it expects to pay out "millions" of pounds in compensation to passengers impacted by its disastrous timetable change earlier this year.

The group, which also runs the Great Northern and Southeastern franchises, said it was contacting tens of thousands of customers affected by the bungled changes in May, which led to widespread cancellations and delays across Britain's rail network.

David Brown told the Press Association the industry was left "mortified" by the disruption, but blamed a "systemic industry failure" for the chaotic timetable overhaul.

The group insisted it has been proactively contacting those affected on its Govia Thameslink Railway (GTR) services to offer compensation, with 30,000 customers contacted since the beginning of last week alone.

It expects to pay out "millions" of pounds in compensation.

Despite the timetable woes, annual results revealed Go-Ahead notched up a 6.5% rise in pre-tax profits to £145.7 million for the year to June 30, sending shares soaring 16% higher.

But it warned it may face a Government penalty - or even see franchises terminated - following the severe timetable disruption, which saw it breach some of its contractual targets.

Mr Brown vowed to contest any penalties from the Department for Transport, saying the firm only received the timetable changes from Network Rail weeks before they were due to come into effect.

He said: "It was a systemic industry failure and the biggest timetable changes for a generation."

"We are all mortified by it, but we are getting it right now," he added.

The group's Thameslink and Great Northern services were the worst affected, with eight weeks of disruption, but there were cancellations and delays across the industry.

Mr Brown said the group is providing a "much improved train service" since an interim timetable was introduced in mid-July, and is "confident" of having the full changes in place by December 9.

Full-year results show Go-Ahead's underlying operating profits fell 9.8% to £135.9 million, while revenues slipped 0.6% to £3.5 billion.

It said it expected a "robust" performance over the new financial year.

Go-Ahead's rail division saw operating profits tumble 25.7% to £44.5 million, largely due to the recent loss of the London Midland franchise.

The group's Southeastern contract expires next March and has been put out to tender, but Go-Ahead is one of the short-listed bidders for the service.