Johannesburg - Four South African match officials were offered $30 000 (R361 461) to fix an international club game in Nigeria this weekend, their country's national soccer association said Thursday.

Referee Victor Gomes, assistant referees Johannes Moshidi and Athenkosi Ndongeni, and fourth official Thando Ndzandzeka were offered the bribe in cash ahead of Nigerian team Plateau United's Confederation Cup game against Algerian club USM Alger in Lagos on Saturday, the South African Football Association (SAFA) said.

SAFA said Gomes immediately reported the incident to the Confederation of African Football (CAF), which runs the Confederation Cup.

CAF has opened an investigation. No details were given on who was suspected of offering the bribe.

Plateau United won the game 2-1. The second leg is next week in Algeria.

The playoff will decide who reaches the main group stage of the Confederation Cup, Africa's second-biggest club competition after the African Champions League.

Africa has been a fertile ground for match-fixing in recent years.

A World Cup qualifier between South Africa and Senegal in 2016 was ordered by FIFA to be replayed after Ghanaian referee Joseph Lamptey was found guilty of fixing the game by awarding Bafana Bafana a penalty for a non-existent handball by a Senegalese player.

It was the first time a top-level soccer game was replayed because of match-fixing.

Lamptey was later banned for life by FIFA, which detailed other games stretching back years where his actions came under suspicion.

This month, the referees' body in Malawi asked the national soccer association to increase the amount it pays referees and match officials, which is currently about $5 (R60) each per game.

The referees' body argued that the low wages increased the likelihood of match officials fixing games for money.

That request by the Malawian referees union followed a case in the southern African country last year when four match officials were banned for life for agreeing to fix a club game for a total of $20 (R241) between them.