Spokesman Vishnu Naidoo said that the police found no trace of any explosives. "We believe it was hoax call."

He said that police received an anonymous call at around 10:00 am (0800 GMT), saying a bomb had been planted in the Old Mutual building in the center of the city and the bomb was going to go off at 2:00 p.m. (1200 GMT).

Shortly after they had received the call, he said, four sniffer dogs went through the building but found no trace of any explosives.

The police believed that the threat call might be linked to the start of the US-led war in Iraq.

It is obvious that the South African government headed by President Thabo Mbeki and its people oppose the unilateral action against Iraq and 31 South Africans are now in Iraq as human shields.

The United States embassy in Pretoria and three consulates in Johannesburg, Cape Town and Durban were closed to the public for security reasons on Thursday.

They are also on a heightened state of alert as were all US embassies and consulates around the world, said embassy spokeswoman De Angela Burns-Wallace.

A group of about 30 people outside the consulate in Johannesburg carried placards and shouted "No blood for oil."

Around 40 demonstrators protested outside the embassy, with a group called the Anti-War Coalition, saying the protest would continue 24 hours a day until the end of the war.

The British government buildings in South Africa remained open for business as usual, said spokesman Nick Sheppard. Staff members were on alert and a high state of vigilance.

"Although there is an increased state of vigilance around the world, I am not aware of any specific threat against British interests or nationals in South Africa," he added.

(Xinhua News Agency March 20, 2003)