(CNN) The family of Africa's youngest billionaire who was kidnapped last week have offered a reward of one billion shillings ($440,000) for information leading to his rescue.
Tanzanian tycoon Mohammed Dewji, 43, was seized by two gunmen as he left the gym of the Colosseum Hotel in Dar es Salaam last Thursday.
Police said the abductors, who are believed to be foreign nationals, drove into the hotel in the Tanzanian capital and opened fire before bundling Dewji into a car and speeding off.
The kidnappers entered the gym through hotel gates police believe were left open deliberately.
The motive for the kidnapping is still unknown. Police told CNN Monday they have yet to receive a ransom demand for the young billionaire. Around 20 men have been arrested in connection with the incident, they added.
"The family would also like to assure any person(s) giving information that all of this will remain strictly confidential and shall stay solely between person(s) and the family," according to family spokesman Azim Dewji.
According to Forbes Magazine, Dewji is Africa's youngest billionaire and has a net worth of $1.5 billion. He runs the METL group, a family business founded by his father in the 1970s, that operates across six African countries.
The pan-African conglomerate has massive holdings in textile and food and beverage manufacturing businesses across Africa.
Dewji popularly called Mo, launched a beverage brand called Mo Cola to compete with Coca Cola in 2014.
In 2016, Dewji signed The Giving Pledge in 2016 and promised to donate at least half his fortune to philanthropic causes.
He served two terms in Tanzania's parliament before he resigned in 2015 to dedicate more time to the family business.