Singapore posted new public speaking rules on Friday, clarifying that foreign companies and individuals need a permit to sponsor or take part in certain events, in an amendment that will restrict foreign support for an annual gay-rights gathering.
The Ministry of Home Affairs (MHA) did not mention any particular event, but authorities warned in June they would take steps to prevent foreign firms from funding or supporting the city-state's gay-pride event.
Sponsors for this year's rally in June included Facebook, Google and Goldman Sachs.
The rally has been held since 2009 under conservative Singapore's stringent public assembly laws at a Speakers' Corner in a downtown square, where Singaporeans can speak their mind without a permit.
Even for Singaporeans, however, there are limits on what they can say on some issues, such as ethnicity and religion. The government of the multi-ethnic island is sensitive about anything that it thinks could upset social harmony.
The MHA said preventing foreign entities from interfering has been its position since the public speaking rules were introduced in 2000 and the changes, which will come into effect in November, are meant to reinforce the principle.
"The government's position has always been that foreign entities should not interfere in our domestic issues, especially those of a political or controversial nature," the ministry said.
"Foreigners will need a permit if they organize or participate in an event at the Speakers' Corner, subject to assessment."
Sex between two men is illegal in Singapore and punishable with up to two years in prison, though the law is rarely enforced. The law, which dates back to the island's colonial period, makes no mention of lesbians.
Observers say foreign companies are unlikely to get a permit to get involved in the event in 2017.
Neither Singapore citizens nor Singaporean companies "incorporated or registered in Singapore and controlled by a majority of Singapore citizens", need a permit, according to the ministry's revised rules.
Singaporeans can link up with Speakers' Corner through means such as teleconferencing or pre-recorded messages, the ministry said.
Human Rights Watch has criticized the government's stance on foreigners' involvement in the Pink Dot event, saying it infringed freedom of expression.
This year, Singapore organizers of the musical "Les Miserables" cut a scene in which two male actors kiss after complaints from the public.