By Mark Gleeson BBC Sport, Cape Town

The match-fixing allegations come just weeks after the country won the right to host the 2010 World Cup

Top football referees plus officials from newly-promoted Umtata Bush Bucks made brief court appearances in South Africa on Monday as the police probe into match-fixing continued.

But as the number of arrested officials moved towards 20, the national police commissioner Jackie Selebi has imposed a clamp down on his investigators giving information to the media.

"We have been instructed by the National Commissioner to stop communicating with the media and give the police time to wrap the investigation," said a spokesman for Senior Superintendent Selby Bokaba.

The latest arrest was of a match commissioner in Welkom on Sunday, although his identity is yet to be known.

17 arrested on bribery charge

On Monday, Petros Mathebela, Simon Motau and Walter Mochubela, all of whom are Fifa-accredited referees, appeared in court to answer charges of corruption.

The trio were handed bail after appearing in court in East London and Bloemfontein.

Corrupt officials are being charged in the magisterial districts in which the match-fixing is alleged to have taken place.

It now seems that Mathebela is unlikely to take charge of the World Cup qualifier between Sudan and Libya in Khartoum on Saturday.

The official had been put in charge of the match by Fifa.

Also in court in East London was Stru Pasiya, the owner of Umtata Bush Bucks, who have just won promotion to the premier league.

Pasiya and another club officials are also charged but since they will only go on trial later this year it is unlikely that their club's promotion to the premier league will be affected as the South African Football Association will be loath to prejudge any court decision.