A security expert has warned that the country is vulnerable to terror attacks because South Africans in general do not perceive themselves to be a target.

The US embassy in Pretoria was evacuated for about an hour on Tuesday morning, apparently following a bomb scare.

The evacuation comes just weeks after all US government facilities in the country closed for two days because of a security threat reportedly linked to al-Qaeda.

Researcher Anneli Botha says terrorist threats will become even more prevalent in the run up to and during next year's FIFA World Cup.

"With the 2010 world cup being hosted in South Africa it is not the country being targeted, it is the event that is the target," says Botha.

Meanwhile, International Relations Director-General Ayanda Ntsaluba says South Africa's authorities are working closely with their US counterparts to deal with perceived security threats.