A missing passport photograph is threatening Eric "the Eel" Moussambani's chances of making an Olympic comeback but the swimmer is still desperately hoping he can make it to Athens.

Moussambani, who was given the nickname after swimming very, very slowly at the Sydney Games four years ago, has been told by authorities in Equatorial Guinea that they could not find a photograph to complete his authorisation to compete.

"The Equatorial Guinea Olympic Committee told me if I wanted to go to Athens I had to be in my country with the rest of the athletes going to the Games," Moussambani, who trains in Spain, told Marca newspaper.

"Since I got back they told me that I was short of a passport photograph and because of that they couldn't give me authorisation.

"I'm waiting and waiting. I wasn't to go. I want to demonstrate to the world that I can swim better. I've taken a minute off my time."

Moussambani shot to international fame in the 2000 Sydney Olympics, where he finished last in the 100-metre heats in a time eight seconds slower than Australian Ian Thorpe's effort over 200 metres.

He had taken up swimming nine months before the Games in a nation with two pools but the Australian crowds cheered his performance with enthusiasm rivalling that for a world-record swim.

Swimwear company Speedo promptly sponsored him and over the next 12 months Moussambani was flown around Europe doing interviews and launching products.