Prosecutors said they were holding Ghosn, 64, for allegedly collaborating to falsify securities statements and underreport $44.6 million in income from 2011 to 2015.
China's Xi Jinping and US Vice President Mike Pence traded barbs as the summit, attended by Jacinda Ardern, kicked off.
In addition to the summit, Jacinda Ardern will be visiting a produce market, which New Zealand aid money helped to renovate.
Visitors will gain visa-free entry for three months and companies with offices in Singapore will be able to send employees to work there for eight years.
"I'll have succeeded if kids say to their parents they want to be a politician and they think 'great.'"
Amnesty has criticised the failure of Suu Kyi and her government to speak out about military atrocities against the Rohingya Muslim population.