Kadeena Cox won the 100m and missed out on a sprint double in Doha

IPC Athletics World Championships Venue: Qatar Sports Club, Suhaim Bin Hamad Stadium, Doha Dates: 22-31 October Coverage: Daily reports on the BBC Sport website, plus coverage of key races on BBC Radio 5 live and BBC World Service

Sprinter Kadeena Cox's disqualification was described as "unduly harsh" after she was one minute late to the call room before her T37 200m semi-final at the IPC Athletics World Championships.

Cox, 25, who was expected to add to her 100m gold, delayed her arrival to avoid the Doha sun exacerbating her multiple sclerosis (MS).

But organisers said they were enforcing tighter procedures.

"I'm absolutely gutted for Kadeena," said British head coach Paula Dunn.

"This is an incredibly difficult situation for the athlete and her support team. Whilst we feel this is an unduly harsh decision, we will learn from this experience and move on."

Cox, who was a keen sprinter before suffering a stroke and contracting MS in 2014, and fellow medal contender Mandy Francois-Elie of France were the first athletes to be penalised for this trangression.

Stricter procedures came after the Great Britain team had appealed against the late arrival of American wheelchair racer Alexa Halko to the call room ahead of the T34 100m, which was won by Hannah Cockroft.

Baroness Grey-Thompson, GB Paralympic legend & BBC pundit: "The biggest loser here is Kadeena. Whatever has happened up to now in the championships, unfortunately this is the ruling and the athlete and coaches and team need to make sure competitors are at the call room at the correct time. It sounds harsh but you have that responsibility. "Why the competition organisers have waited until day eight to enforce the rule, I don't know. It should have been sorted from day one and it should never have come to this."

International Paralympic Committee communications director Craig Spence told BBC Radio 5 live: "An official communication went to every team on Wednesday night via email and it was posted in the pigeonholes of every single team. There was a reminder that went out on Thursday morning that the rule would be fully enforced.

"One of the teams who complained was Great Britain. The rule has now been enforced and it is Kadeena Cox and Mandy Francois-Elie who have come a cropper unfortunately, but we have to apply the rule."

Sophie Hahn ran a new personal best

Cox is also a talented cyclist, winning a national title in Manchester last month, but has yet to confirm which sport she will concentrate on in the build-up to the 2016 Rio Paralympics.

Teenagers win silvers for GB

Meanwhile, teenage sprinters Sophie Hahn and Maria Lyle added to the Great Britain medal haul with silvers on day eight of competition in Doha.

Hahn, 18, ran a new personal best of 26.82 seconds to finish behind Russian Margarita Goncharova in the T38 200m.

There was a European record of 13.92 for Lyle, 15, in the T35 100m but she was edged out by 14-year-old Australian rival Isis Holt.

Newcomer Shaun Burrows claimed bronze in the T38 400m to take the GB total to 27 medals with two days still to go.

Browne sets new world record

Elsewhere, American Richard Browne stormed to victory in the T44 100m in a new world record time of 10.61 seconds - beating the 10.72 of compatriot Jarryd Wallace set in August in Toronto - to add to his 200m success.

In the absence of Wallace and Britain's defending champion Jonnie Peacock, Browne, who is now based in Cambridge and working with Peacock's old coach Hayley Ginn, was a class apart.

Silver went to South Africa's Arnu Fourie (10.93) with Brazil's double amputee Alan Oliveira third (11.02).

"I definitely wanted to break that world record today," Browne told BBC Sport. "I wanted to run fast and show everyone that I am the best at what I do. But that's not the end - I want to keep pushing and running fast and be the best in the world.

"I watched the Diamond League this year so I knew this was a fast track. I felt confident all week about the 100m but I know everyone will be back in Rio and I can't wait to see what happens there."