The US government has issued a travel alert warning its citizens that South Africa faces a heightened risk of terrorism during the football World Cup.
It says that large-scale public events present an attractive target.
"There is a heightened risk that extremist groups will conduct terrorist acts within South Africa in the near future," the State Department says.
The department says it has no information on any specific, credible threat but notes that such threats have been reported in the media.
Swift denial of '80% chance' story
South Africa has mobilised thousands of specially trained police to deal with fans' safety, and security officials have moved swiftly to deny claims in Johannesburg's Sunday Times about a briefing to the US Congress counter-terrorism caucus last week.
The story quotes Ronald Sandee, director of NEFA, a foundation that investigates terrorist activities, as saying there is an 80% chance of attack.
The National Joint Operational and Intelligence Structure, which coordinates security operations for the World Cup, says there is no known specific terror threat against the tournament.
About 350,000 people are expected to visit South Africa for the World Cup, which starts on 11 June.