from Athletics Northern Ireland Smyth has been forced to withdraw from next month’s Paralympic World Championships in New Zealand.
The double Paralympic champion missed the Commonwealth Games in October because of a back injury and the ailment is continuing to bother him.
Derry man Smyth has been unable to resume full training so his decision to opt out of the event is not a surprise.
Smyth also competes in able-bodied athletics and was a 100m semi-finalist at this year’s European Championships.
The Londonderry athlete became the first Paralympian to compete at a European Championships when he participated in Barcelona during the summer.
Smyth, who was hoping to repeat his previous double triumph at the World Paralympic Games, said he was "extremely disappointed" at having to withdraw from the Christchurch championships.
"Unfortunately my training is progressing very slowly and I would not be fit enough to defend my titles," said Smyth.
"I’d like to wish my team mates the best of luck at the Championships.
Irish Paralympic Athletics chief James Nolan
"I look forward to returning to competition in the Summer and to achieving the London 2012 Paralympic qualification times at the earliest opportunity."
Smyth’s withdrawal will be a major blow to the Irish team although his team-mate Michael McKillop will be fancied to land at least one gold in New Zealand.
Irish Paralympic Athletics chief James Nolan agreed that the "right decision has been made to withdraw Jason from the team".
"Jason’s professional support team have been doing everything in their power to have him ready for the Paralympic Athletics World Championships," said Nolan.
"Unfortunately the lead in time to the championships was too short to fully rehabilitate the injury."
Smyth’s back problem is bone-related which has slowed down his recovery.
The double Paralympic champion ran a new NI record of 10.32 in mid-June and a wind-assisted 10.27 but his build-up to the Europeans was then affected by injury.
The Eglinton man was unable to race for a six-week period before the European Championships.
The injury had to be carefully managed in order to make the start line at the Europeans.