Police in Tanzania are investigating the kidnapping of Mohammed Dewji, the country's richest man, who was seized this morning on his way to the gym in the country's main city, Dar es Salaam.

But how frequent are such incidents?

The city's name comes from Arabic, and literally means Abode of Peace. And Dar es Salaam is very safe, in comparison to Lagos or Johannesburg, the main cities in Nigeria and South Africa respectively.

Although Tanzania has seen a wave attacks and abductions of opposition politicians and perceived government critics, this is the first time a businessman of Mr Dewji's standing has been kidnapped in the country.

Businessmen have never felt at risk of being kidnapped and they often move around on their own. Some may have chauffeurs, but not bodyguards.

So Mr Dewji's abduction has come as a huge shock.