Referee Ibrahim Chaibou of Niger is free to officiate in matches while FIFA investigates his handling of an international friendly between Nigeria and Argentina that is suspected of being manipulated, football's governing body said Wednesday.

FIFA said it was too early in its probe to suspend Chaibou from duty.

''FIFA has not opened a formal disciplinary proceeding into this matter, but is at the stage of 'pre-investigation.' Therefore, no provisional suspension can be pronounced,'' the governing body said in a statement.

Chaibou awarded Argentina a penalty for handball in the eighth minute of injury time in the team's 4-1 loss in Nigeria last Wednesday.

FIFA said it was studying betting patterns during the match which ''forms part of a wider ongoing FIFA investigation.''

In May 2010, Chaibou gave three penalties for handball in South Africa's 5-0 win over Guatemala in Polokwane that was the World Cup host's final warmup match.

Chaibou was the referee when Bahrain beat a fake Togo team 3-0 last September. That match appeared to confirm growing fears that international matches were being targeted for betting coups by organized crime gangs.

The Niger official joined FIFA's approved list of international officials in 1996 and must stand down this year after reaching the mandatory retirement age of 45.

The Confederation of African Football, which proposes match officials for the list, said it was giving FIFA investigators ''any supporting documents and information'' they might need.

''We are cooperating with FIFA and waiting for further investigations to be able to take a decision,'' CAF secretary general Hicham el-Amrani told The Associated Press, referring to Chaibou's international status.

Chaibou also officiated two friendlies in South America in the past season. He handled Venezuela's 3-1 victory in Bolivia in October, and one month later awarded each team a penalty in Ecuador's 4-1 home win over Venezuela.

Responding to the spread of match-fixing, FIFA and its six confederations now have power to veto unsuitable referee appointments, and require organizers of international fixtures to provide details of match officials two months before kick off.