The Ministry of Home Affairs (MHA) said on Tuesday (June 7) it will "take steps to make it clear that foreign entities should not fund, support or influence" events held at Speakers' Corner, like the annual Pink Dot event last Saturday.
This year's event - the eighth such - attracted 18 sponsors, twice as many as last year. The corporate sponsors included multinationals such as Google as well as banks like JP Morgan and Goldman Sachs.
Apple, Facebook, Visa and General Electric were first-time sponsors.
In its statement, MHA noted that the lesbian, gay, bisexual and transgender (LGBT) community expresses its views on issues of concern to it during Pink Dot.
"The Government's general position has always been that foreign entities should not interfere in our domestic issues, especially political issues or controversial social issues with political overtones. These are political, social or moral choices for Singaporeans to decide for ourselves. LGBT issues are one such example.
"This is why under the rules governing the use of the Speakers' Corner, for events like Pink Dot, foreigners are not allowed to organise or speak at the events, or participate in demonstrations."
It did not say what action it will take, and whether there will be legal penalties. It also did not say whether or not an MNC with a Singapore-registered arm is still defined as a foreign company.
MHA said the statement was in response to "media queries as to whether foreign companies can provide sponsorships for the Pink Dot event", but did not specify which media outlet posed the queries.
The ministry also said that, in the context of LGBT issues, this applies to events that advocate the LGBT cause, such as Pink Dot, as well as those that oppose the LGBT cause.
Pink Dot has met with opposition from religious groups. In 2014, Muslim religious teacher Noor Deros started a Wear White campaign to signal opposition to homosexuality, while Faith Community Baptist Church senior pastor Lawrence Khong urged followers to dress in white on the Pink Dot weekend.
In response to the MHA statement, a Pink Dot spokesman noted that the event has seen support from Singaporeans from all walks of life, including "a significant portion of its corporate citizens".
"Our corporate sponsors that have supported us over the years are all registered and incorporated in Singapore," said the spokesman.
In pushing for greater visibility for the LGBT community, "we have done all we can to ensure Pink Dot SG stays within the law", he said.
Attendance at Pink Dot rose from 2,500 in its first year in 2009 to 28,000 last year. This year's local sponsors include the restaurant PS.Cafe and Cavenagh Law.