You can be arrested by the Police or an enforcement agency such as the Central Narcotics Bureau (CNB), Commercial Affairs Department (CAD), Corrupt Practices Investigation Bureau (CPIB) and Immigration & Checkpoints Authority (ICA).
The Police or enforcement agency can arrest you without obtaining the Court’s written permission (also known as a Warrant) if they have a reasonable suspicion that you have committed an arrestable offence and you need to be detained for investigations or to be produced in Court to be formally charged for committing an offence.
Examples of arrestable offences are:
Assault or use of criminal force to deter a public servant from discharge of his duty
Theft
Cheating
Criminal breach of trust
Criminal intimidation
Criminal trespass
Dishonestly receiving or retaining stolen property
Extortion
Robbery
Rape
Unlawful assembly
Rioting
Voluntarily causing grievous hurt
Voluntarily causing hurt by dangerous weapons or means
Wrongful confinement
Wrongful restraint
Sexual assault by penetration, without consent (including oral or anal sex)
Commercial sex with minor under 18 years of age
Doing obscene act or reciting obscene song in a public place
Trafficking, possession or consumption of drugs
Offences under the Computer Misuse and Cybersecurity Act (formerly named the Computer Misuse Act)
Offences under the Vandalism Act
The full list of arrestable offences is found in the First Schedule of the Criminal Procedure Code which may be accessed here.
For all other offences (also known as non-arrestable offences), the Police or enforcement agency will generally need to obtain a Warrant (or written permission) from the Court before they can arrest you.