Ershad breathed his last at the Combined Military Hospital in Dhaka around 7:45am on Sunday, Sunil Subho Roy, the party chairman's political and press secretary, told bdnews24.com.
The 90-year-old deposed military dictator has been suffering from myelodysplastic syndrome or a low-level of haemoglobin in his blood for long.
He was diagnosed with lung infection and kidney ailment after he was admitted to the CMH on June 22.
Speaking at a media briefing on Saturday, his brother and GM Quader said, " None of Ershad's organs are functioning.”
Ershad returned to Bangladesh on Dec 26, just ahead of the general election after treatment in a Singapore hospital.
He pulled himself out of the electoral race in the Dhaka-17 seat citing his illness, but contested in the Rangpur-3 constituency without campaigning and won the election.
In April, Ershad formed a trust and donated all of his assets to it.