Organisers of the event in South Africa said extra measures were drafted in for yesterday's semi-final between Australia and Sri Lanka, and for tomorrow's game between India and Kenya.
It is just the latest impact on sport as tension rises as the US-led war effort against Iraq gathers even greater momentum.
Already a number of big names have pulled out of golf events in the Middle East amid security fears, and a number of events have been cancelled - among them the FIFA World Youth Championships.
Said Patrick Ronan, head of security at the Cricket World Cup: "Given the events in Iraq there is a heightened level of security at games.
"There will be a heightened level of security, both in the private sector and state sector."
Meanwhile, Zimbabwe is set to decide later this month if it is to go-ahead with its planned summer tour of England.
England cricket chiefs enraged Zimbabwe when it refused to let its team play in the country during the current World Cup.
Said ZCU chairman Peter Chingoka: "We are having discussions."
