Benjamin Glynn, 40, was found guilty on four charges over his failure to wear a mask on a train in May and at a subsequent court appearance in July, as well as causing a public nuisance and using threatening words towards public servants.
Glynn was earlier subjected to a psychiatric assessment ordered by the judge as a result of his conduct and remarks in court.
On Wednesday he asked the court to drop what he called “unlawful charges” and asked for his passport to be returned so that he could go back to Britain to be with his family, according to media outlet CNA.
It quoted the judge as telling Glynn that he was “completely misguided” in is belief that he was exempt from Singapore’s laws on wearing masks.
Glynn represented himself in court and Reuters’ calls and text messages to his phone were unanswered on Wednesday.
The Asian business hub is well-known for its enforcement of strict rules and has jailed and fined others for breaking Covid-19 regulations. Some foreigners have had their work permits revoked for rule breaches.
The city-state has kept its coronavirus outbreaks under control, in part due to its strict enforcement or measures.