Charges were brought in 2019, but he was never convicted.
In a separate case, he was also indicted over his role in calling in miners to crush student protests after his election in 1990.
The bloody crackdown, which became known as the Mineriad, drew widespread international condemnation.
Prior to his latest hospitalisation, Iliescu had been receiving regular medical check-ups at Elias Hospital in Bucharest.
In 2019, he underwent surgery for pericardial effusion – a condition affecting the heart.
Born on 3 March, 1930, in the southern city of Oltenița, Iliescu had largely withdrawn from public life in recent years, though he occasionally shared written messages on his personal blog.
His final post, on 19 May, congratulated Bucharest’s liberal, pro-EU mayor, Nicusor Dan, on being elected president.