Racial and religious harmony is vital to Singapore and has allowed Singaporeans to live together in peace over the years.

But words or deeds touching on race or religion have the potential to create fault lines within our society and such bonds, "once frayed, let alone sundered, cannot easily be repaired and we must therefore remain vigilant against any threats to racial and religious harmony", said the Attorney-General's Chambers (AGC) on Saturday.

The statement comes on the back of the Apr 19 arrest of cartoonist Leslie Chew, who is being investigated under the Sedition Act for "a series of racially insensitive cartoons which are circulating online".

The AGC said it was aware of the interest in Mr Chew's case and was responding to queries "on the general principles as to when investigations would be conducted, and action taken against persons".

"Every day, there are hundreds of commentaries, if not more, on socio-political matters both in the mainstream media and online. Many of these do not contravene the law, and no legal action will be taken by the Attorney-General's Chambers on behalf of the State, even though some may contain factual inaccuracies," said the spokesman.

"(But) where statements are made, or actions are taken, which insult a particular religion or race, or seek to engender hatred amongst races or religious groups, or which suggest that the Government is using race or religion for its own purposes, then a response will follow. Where the statements or actions are heinous, a firm line will be taken. For example, the burning of the Koran or the Bible will not be allowed in Singapore under the cover of freedom of speech or expression."

The AGC added that the rule of law is a fundamental tenet of Singapore's society and warned that action will be taken in respect of any statement or action that seeks to impugn or undermine the independence of the judiciary here.

"Unwarranted allegations of bias or partiality strike at the heart of the judicial process, threatening the very institution that protects the rights of all Singaporeans. Such unfounded statements cannot be left to stand unchallenged and unpunished."