Sprinter Leon Reid has written an open letter to IAAF president Lord Coe in a last-ditch attempt to be cleared to run for Ireland at the World Championships.
Reid, 22, competed for Northern Ireland at the 2014 Commonwealth Games and now wants to switch international allegiance from GB to Ireland.
Despite starting the transfer process a year ago, it has yet to be completed.
Reid's letter asks Lord Coe to help push through his transfer so he can race in London.
The Bath-based athlete, who won European medals at junior and under-23 level for Britain, says he wants to run for Ireland in honour of his Belfast-born biological mother who died last year.
Reid, who has a 200m personal best of 20.38 seconds, spent much of his childhood in the British care system before being fostered by a family who have strong Irish connections.
The athlete's letter to the IAAF president says that the governing body's decision to allow eight Russian athletes to compete under a neutral banner in London provoked him to make his late plea.
Reid's application stalled earlier this year when the IAAF opted to halt all international transfers, pending a review, because of concerns over the number of African athletes switching nationalities.
"I am scared that with the final date for selection this Sunday, 23 July, that my international transfer will not go through and I will miss out on competing in London in August," said Reid, who ran the World Championship 200m qualifying standard when finishing third at last month's British Championships.
"This is despite the transfer process starting well before the freeze came into place and had it been handled diligently, it would have been completed."
Reid's letter says that British Athletics' performance director Neil Black assured him last year they would not hinder his switch.
European Junior win for Irish teenager
Meanwhile, Irish sprinter Gina Akpe-Moses clinched a surprise 100m gold medal at the European Junior Championships in Italy.
Eighteen-year-old Akpe-Moses, who runs for the Blackrock club in county Louth, clocked 11.71 seconds to triumph in Grosseto.
Akpe-Moses, who was born in Nigeria but moved to Dundalk at the age of three, has a personal best of 11.56 seconds.
She moved with her family to Birmingham in 2014 but has continued to compete for Ireland and won a European Youth Olympics silver medal two years ago.
Also at the European Juniors, 16-year-old Kate O'Connor achieved the Commonwealth Games heptathlon consideration standard for the second time as she finished eighth - improving her Northern Ireland record in the process.
O'Connor, who competes for the St Gerard's club in Dundalk, produced 5,759 points while her Ireland team-mate Elizabeth Morland took fifth place with a new Irish senior record of 5,801.