Letter of Introduction (LOI) to be issued by local contact in Singapore:
For Social Visitors, any Singapore Citizen or Singapore Permanent Resident, who is at least 21 years old, can act as a local contact.
For Business Visitors, a Singapore registered company / organisation can act as a local contact. The LOI must be signed by a Singapore Citizen or Singapore Permanent Resident, who is at least 21 years old, only.