James Raj, 35, was charged with hacking into the website of the Ang Mo Kio town council -- a district whose team of MPs representing it in parliament is led by Prime Minister Lee Hsien Loong -- on October 28, and posting the image of a Guy Fawkes mask.
The hacking took place three days before a self-proclaimed spokesperson for the Anonymous group appeared in a video on October 31 to demand the scrapping of a new law requiring news websites to obtain annual licences.
Singapore strictly regulates the traditional media, but insists the new licensing rules do not impinge on Internet freedom.
A charge sheet seen by AFP mentioned no direct links between Anonymous and Raj, who is also facing drugs charges.
More From This Section
According to the charge sheet, Raj identified himself as "The Messiah" and carried out the intrusion from an apartment in neighbouring Malaysia's capital Kuala Lumpur.
The same moniker was used by someone who hacked a reporter's blog on the website of the pro-government Straits Times newspaper on November 1.
He was charged under the Computer Misuse and Cybersecurity Act. He faces a maximum fine of USD 8,000 and imprisonment of up to three years, or both.
State prosecutors said they were seeking to have Raj remanded at a mental health facility for a psychiatric evaluation after he claimed he suffered from a number of mental disorders, including attention deficit hyperactivity disorder (ADHD) and borderline personality disorder.
Raj's lawyer M Ravi opposed the continued detention of his client and another hearing was scheduled later today.