A 49-year-old cleaner collapsed and died at the rooftop of a hall of residence in Nanyang Technological University (NTU) on Friday afternoon.

Mr Ibrahim Moidu, who has worked at water tank sterilising company YPI Clrwater for about six years, was preparing to clean a water tank at the top of the hall when he complained he felt tired, said his supervisor Mr Eksan Othman.

"He just sat down but fell over and started bleeding from his nose and mouth," said Mr Othman.

The Singapore Civil Defence Force said they received a call at around noon and paramedics responding to the case pronounced Mr Moidu dead at the scene. Police investigations are ongoing.

Mr Othman described Mr Moidu as an "exemplary worker" and said his company will be helping Mr Moidu's family sort out insurance claims since he died on the job.

Mr Moidu's siblings told The Straits Times that their brother - the fourth out of seven children - was healthy and driven, travelling from his home in Johor Bahru to Singapore for work every day. His sister Lela said he had been suffering chest pains and had visited a doctor last week. Their family has a history of heart problems, she added.

His wife and three children live in Indonesia and he had planned to visit them in Sukabumi next month. They will now be making their way to Singapore for the burial instead.