Network Rail (NR) staff travelling on business spent £1.3 million on UK flights in the last two years as it was cheaper to fly than to take the train.

Employees of NR, a public sector body, took 8,353 domestic flights in the period from April 2013 to March 2015 and also spent £1.1 million on 2,907 international flights.

Former operations managing director Robin Gisby spent most on domestic flights during this period, taking 15 flights between January 2013 and September 2014 costing £2,250 and also spending £4,430 on an international flight.

Mr Gisby, who left the company earlier this year, faced severe criticism for NR's Christmas engineering overruns which led to chaotic scenes at Finsbury Park station in north London.

Some of the international flights were as far afield as Japan and Australia. NR said today that staff are allowed to travel in business class on any flight which is longer than five hours.

The figures on staff travel were obtained by The Sun in a request under the Freedom of Information Act.

Around 90% of the domestic flights were to Scotland.

An NR spokesman said: "If employees have to attend a 10am business meeting in Scotland it is to cheaper to fly up than take the train the night before and have to pay for overnight accommodation."

He went on: "For the majority of staff travel rail is much the better way to go. A total of £1.3 million was spent on flights in 2013/14 and 2104/15 but £32 million was spent on rail travel during that period.

"Network Rail's 35,000 people have to pay the going rate for all travel, be it air, rail or car. Our people are also obliged to use the cheapest method available, sometimes that means by air but mostly we travel by rail."

A not-for-dividend organisation, with no shareholders, NR effectively moved into the public sector in a reclassification of its status last September when its net debt of more than £30 billion came on to the Government's books.

Mick Cash, general secretary of the RMT rail union, said: "The news of this culture of the top brass jetting around in the lap of luxury comes on the very day that we begin balloting 16,000 NR staff for strike action over the threat to their job security and their standard of living.

"Rail staff out there in all weathers, round the clock, battling to keep Britain moving will be disgusted to see the sums spent on luxury flights by their bosses at a time when engineers and signallers are fighting for a fair pay rise."

A spokeswoman for rail passenger watchdog Transport Focus (formerly Passenger Focus) said: "It is no surprise that so many longer-distance journeys were made by air. Unless passengers can book weeks in advance, rail can be prohibitively expensive for many people.

"Less than half of passengers are satisfied with the value for money of train fares. The rail industry needs to address this if it wants to compete with airlines."