Tourism is a cornerstone of the economy, contributing 8 percent of annual GDP and employing about 1 million people.

Some 8.4 million people visited last year, with the number expected to rise to 10 million by 2010, when South Africa hosts the soccer World Cup.

"It looks like there is panic among tourists across the globe but mainly from Africa," said Reynold Thakhuli, spokesman for the Tourism Business Council of South Africa, which is fielding worried calls from major tourist partners overseas.

Germany was among the first countries to issue a travel advisory after mob rampages that have killed at least 42 African immigrants and prompted more than 15,000 others to flee Johannesburg area shantytowns since May 11.

The German Foreign Ministry advised visitors to avoid central Johannesburg and outlying townships.

The U.S. government issued a travel alert that outlined some of the risks of traveling in South Africa at the moment. Americans represent the second largest single group of foreign overseas visitors to South Africa after the British.

"While there have been no reports of American or other non-African visitors being targeted, these incidents of mob violence have sprung up quickly and proven difficult for local authorities to control," the U.S. government said.

Canada also has urged its citizens to avoid trips to townships, which are a common feature of group package tours to South Africa.

Soweto, which has not been touched by the violence, is the township most often included on such tours.

"Some tours to Soweto have been cancelled ... in response to international concerns," said Angela Shackleford, general manager for touring and safaris at Thompson Tours, one of South Africa's largest tour operators.

While those in the travel industry say they have not experienced a significant drop in bookings by foreign visitors, they admit that there have been some cancellations since the violence began.

About one-third of those expected to attend a recent African businesswomen's conference in Cape Town cancelled. Most of the cancellations came from Nigeria and Guinea.

Tourism council spokesman Thakhuli noted that 60 percent of South Africa's visitors came from other parts of Africa.

Officials in Cape Town, the gem of the tourism sector, have vowed to respond strongly and quickly to any groundswell of anti-foreign or other violence. The city has not been affected by the current wave of attacks.