A judo athlete and four officials from the Congo have vanished in London, joining seven other athletes who have gone missing since the Games began.
Democratic Republic of Congo's Cedric Mandembo, who lost his only judo match in 49 seconds to Russian Alexander Mikhaylin in the 100 kg category, disappeared after Sunday's closing ceremony.
His judo coach Ibula Masengo, along with boxing trainer Blaise Bekwa, and Guy Nkita, the country's technical director of athletics Guy Nkita have also left the Athletes.
The Home Office would not comment on individual cases, but the disappearance of the Congolese Olympians adds four to the seven other Cameroon athletes and officials who are apparently still in the country.
Officials are looking for five boxers, a swimmer and a football player from Cameroon, but the athletes are permitted to stay in Britain until November, when their visas expire.
The five boxers told the BBC they had been threatened by their own delegation, who had tried to confiscate their passport, and halved their bonuses.
The other missing boxers are Thomas Essomba, Christian Donfack Adjoufack, Abdon Mewoli and Serge Ambomo, plus swimmer Paul Ekane Edingue and female footballer Drusille Ngako.
All seven have visas to stay in Britain until November, British Olympic officials said last week.
Essomba told the BBC: "We are not staying here because we don't like our country, but want to practise the sports we love.
"We want to become professional. We cannot return to Cameroon. If we return, we will not practise anymore."