Ibrahim Chaibou, from Niger, has gone to ground since it was revealed that FIFA are looking into suspicious betting patterns surrounding the Argentina v Nigeria friendly on June 1.

FIFA's head of security Chris Eaton told Press Association Sport: "We are trying hard to track down the referee and we are confident that we will succeed."

Nigeria won the match in Abuja 4-1 - they were leading 4-0 until Chaibou awarded Argentina, who fielded a second-string side, a penalty for handball in the eighth minute of injury time. Television replays showed the ball had hit a Nigerian player's shin.

The fourth official had indicated five minutes of injury time should be played. While the score was 4-0 to Nigeria, a huge amount of money in the Asian gambling markets was bet on a fifth goal being scored in the match.

Chaibou has been involved in controversial games before. He was in charge of the match last September where Bahrain beat a fake Togo team 3-0, which is also being investigated for possible match-fixing.

In May 2010, Chaibou awarded three penalties for handballs as South Africa beat Guatemala 5-0 in a World Cup warm-up match.

Chaibou has been on the FIFA international referees list since 1996 but must stand down this year after reaching the mandatory retirement age of 45.