A source from the office of the Secretary of State for Communities told Lusa that the Portuguese embassy in Indonesia "kept in regular contact" with the Portuguese citizen.
"There are ongoing steps with the respective family, to provide the necessary support in these tragic circumstances," she added.
The Portuguese citizen died in a fire that broke out last night in the prison in Tangerang, a city west of the Indonesian capital, which left at least 40 more dead and dozens injured.
"The fire spread quickly and there was not enough time to open some cells," Indonesia's Justice Minister Yasonna Laoly explained during a press conference.
The official added that "40 people died at the scene, another died on the way to hospital" and that eight seriously injured detainees were identified.
Authorities are still investigating the causes of the fire, but suspect an electrical problem to be the cause of the fire.