The Japanese vehicle manufacturing giant said it had been conducting an internal investigation for several months which showed Ghosn had been under-reporting his pay package and identified "Numerous other significant acts of misconduct" including "personal use of company assets".
According to NHK and the Kyodo News Service, Ghosn made almost 10 billion yen ($89 million) over five years through March 2015, including salary and other income from the company, but reported as if he only made 5 billion yen ($44 million), or half of what he had received.
Carlos Ghosn's arrest in Japan over accusations of under-reporting his compensation and personal use of company assets is a bolt from the blue, threatening to remove the leader of the Renault-Nissan-Mitsubishi Alliance in the midst of unprecedented change sweeping through the industry.
Greg Kelly, a representative board member at Nissan, engineered the purchases of the homes used by Ghosn in such locations as Rio de Janeiro and Beirut, the sources said. The allegations also concern another executive, representative director Greg Kelly.
Ghosn began his career at Michelin in France, moving on to Renault.
Mr Ghosn joined Nissan in 1999 after Renault bought a controlling stake and became its CEO in 2001, remaining in that post until a year ago. Saikawa also said during his press conference that the Alliance will not be affected by Ghosn's ouster.
'Nissan deeply apologizes for causing great concern to our shareholders and stakeholders.
Public broadcaster NHK and Kyodo News also reported that Mr Ghosn was to be arrested.
"The initial share price reaction shows how pivotal he is", Citi analyst Raghav Gupta-Chaudhary said on Monday.
He has been credited with turning around both Nissan and Renault before becoming the linchpin of the alliance the firm's later formed.
A man working at a Nissan assembly plant in Tochigi Prefecture north of Tokyo said, "To be honest, I'm disgusted with a series of misconduct scandals" involving Nissan, apparently referring to recent scandals over quality checks. "We will continue our work to identify our governance and compliance issues, and to take appropriate measures".
According to his financial statement, Ghosn earned 735 million yen (around $6.52 million) in fiscal 2017.
"I have to say that this is a dark side of the Ghosn era which lasted for a long time", Mr Hiroto said adding he was still thinking through whether Mr Ghosn was "a charismatic figure or a tyrant".
Ghosn's standing in the complex Franco-Japanese industrial alliance also appears to be at risk.
Ghosn's slow retreat from his roles at each company-including stepping down as Nissan's CEO previous year and suggesting he may step down from his post as CEO of Renault before the scheduled end of his term in 2022-have sparked rumors that he wasn't on board with plans for further integration and might be thinking of leaving the alliance anyway.
The arrest of Ghosn sent shockwaves through the business world and threw into doubt the future of Japan's No.2 automaker and its global alliance with Mitsubishi and Renault. The alliance sold 10.6 million vehicles previous year, more than one in nine of worldwide auto sales.