A "hero" British Army captain running the London Marathon has died after collapsing just three miles from the finish line. Afghanistan veteran David Seath suffered a suspected cardiac arrest as he neared the 23-mile mark during the race on Sunday (24 April).

The 31-year-old, who was a Green Beret, was rushed to hospital but pronounced dead shortly afterwards. He had been raising money for Help the Heroes, a charity which helps soldiers suffering from life-changing injuries during service. His devastated friends now plan to complete the race in his memory by walking the last three miles in aid of the charity.

His close friend, James Walker-McClimens, wrote on a fundraising page: "Today we heard the tragic news that our friend Dave Seath passed away whilst taking part in the 2016 Virgin London Marathon. He was three miles short of the finish line and collapsed on Upper Thames Street.

"His friends and colleagues are planning to complete what he started, in his honour. We will walk as one, the final three miles of the marathon, starting where he fell. We're raising money for Help for Heroes, a cause he ran and died for. He was our friend and hero."

Captain Seath, from Arbroath in Angus, Scotland, was a Fire Support Team Commander with the 29 Commando Regiment Royal Artillery. He had passed out of the Royal Military Academy Sandhurst in 2010 having undertaken a Masters in International Relations and Strategic Studies at the University of Aberdeen. He had served in Afghanistan in 2012, according to his LinkedIn page.

Donations have been flooding in to the charity page now set up in his memory, with £3,300 currently raised. Before his death, Captain Seath had also done charity work for groups helping visually impaired Army veterans, including Royal Blind.

On the eve of the London Marathon, which saw over 39,000 participants, he wrote on his fundraising page: "A big thank you to everyone that has been so generous and sponsoring me for tomorrow. I am sure H4H [Help for Heroes] will be equally as appreciative. Every penny counts and to have broken the £200 mark with your help is very special. Thank you all so much."