All US facilities closed this week apparently after a call from an al-Qaeda splinter group to the embassy, allegedly detailing attacks on several American buildings in South Africa.

The facilities are only expected to reopen on Friday.

The police's Nonkulule Kombatha said officers were monitoring the situation.

"All the South African security agencies, together with the US agencies, are working on the matter, particularly out intelligence services. Hence our police deployment is maximum around the area as far as this challenge is concerned."