The Regional Immigration Office in Tanzania's commercial capital Dar es Salaam has embarked on a crackdown on foreigners without residence or work permits.
The department will also take measures against officials who issue foreigners with fake documents.
Regional Immigration Officer (RIO) John Msumule, made the revelation Tuesday while briefing the Press on last week's operation which, among other things, seized and detained 25 Indian nationals.
The 25, working with Quality Group, were allegedly living and engaging in employment in Tanzania without permits.
Six Chinese working with the Global Leader Company, were also arrested and locked up for allegedly being in possession of fake documents.
Another detainee, a Uganda national named Aisha Talib, was caught with 15 passports belonging to Madagascar and Burundi nationals. Others seized in the crackdown were: six Taiwanese, two Indonesians and a Chinese from the Luck and Spin Company.
They were accused of being in Tanzania without residence or temporary business permits, while they had signed for permanent employment at the company.
Leave the country
Mr Msumule said two of those arrested and detained paid fines and seven had been given five days to leave the country.
He said their operation, which targeted companies, had discovered employers who recruited foreign nationals but failed to process for them the requisite documents to legalise their stay and employment in Tanzania.
The Immigration Office also uncovered a local security company, Alfa Romeo, employing a Malawian national illegally.
Mr Msumule said that at the Quality Centre Group, which runs over 20 separate companies, the Immigration Office identified 128 foreign nationals, 25 of who had neither working nor residence permits.
"Because of that, we have issued a warrant that the owner of the group, Mr Yusuf Manji, who we were told is currently hospitalised, to report in our offices the day he is released so that explains," he said.
The Dar es Salaam Immigration boss also revealed that they had discovered a number of crooked public servants who were involved in producing fake documents, noting that investigations were underway to unmask them.
"We want to ensure that every person in our region lives according to what the law says; we will continue with these operations until the city is clean," he added.