According to Malaysia's immigration department the six men were being detained for being in Malaysia illegally.
Last month all six complained of severe internal aches. They were admitted to hospital and died days later.
The official said on Friday the detainees were believed to have contracted leptospirosis, a disease from water contaminated by rat urine.
AP reports that according to the official the detainees likely contracted the disease in another centre. They were transferred together with some 700 others after a riot there.
Published by Mike Hitchen i On Global Trends, world news, analysis, opinion
Putting principles before profits
Putting principles before profits