Helium-filled balloons were today blamed for causing hundreds of train delays for passengers across Britain each year.

Network Rail highlighted this growing problem as it issued a stark safety warning to train passengers.

The company has recorded 619 balloon-related incidents – nearly two a day – across England, Scotland and Wales in the past year.

Many of the incidents involve balloons getting tangled around high-voltage overhead wires, causing delays while the electricity is switched off and the lines are made safe.

James Dean, chief operating officer for Network Rail’s London North Western route, said: “If you’re on a railway station platform with a foil balloon filled with helium on a string and it comes in contact with the overhead wires carrying 25,000 volts, that could cause huge injury or death.

“Ideally, we’d ask people not to bring balloons into our stations at all. Alternatively, carry them in bags so the risk of them floating upwards is minimised.”

As well as the safety risks and the delays to train passengers, the annual cost of this problem to the British taxpayer is around £1m a year.

The latest such incident took place this week at Smethwick Rolfe Street Station in the West Midlands when a float-away helium balloon got wrapped around the overhead wires. Hundreds of train passengers were delayed.

The cost of the delays from this single incident was £5,000.

Network Rail’s safety message is echoed by the National Association of Balloon Artists and Suppliers (NABAS). NABAS has launched a campaign to ban the launching of foil balloons, sky lanterns or anything with plastic string or ribbons attached.

George Oustayiannis, chairman of NABAS, said: “Balloons bring fun and colour and a sense of celebration to any event, but please dispose of them responsibly, and never release balloons into the atmosphere. Respect the environment and prevent unnecessary danger and delays – please don't let go!”

For more information about how our overhead electric lines work visit networkrail.co.uk/overhead-line-equipment.