The organisers of Singapore's only pride event have banned foreigners from attending this year, following a rule change in the city's laws on demonstrations and political gatherings.

Before the rule change, foreigners could attend Pink Dot as observers, but only locals were allowed to actively "demonstrate" by joining in the human formation of the event's trademark pink dot or holding up placards.

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The event's organisers said in a statement that changes to the city's Public Order Act — laws limiting demonstrations in the country — would mean that the law "no longer distinguishes between participants and observers, and regards anyone who turns up ... in support of an event to be part of an assembly."

Participants form a pink dot at Hong Lim Park in 2015. Image: Getty Images

Singapore's LGBTQ community has struggled to thrive in a city where sex between men remains illegal.

But despite the odds — and rampant pushback from conservative groups in the city — Pink Dot's success has been overwhelming.

The annual pride rally has been held since 2009 in Hong Lim Park — a 0.94 hectare (2.32 acre) corner designated for demonstrations. Organisers said that some 28,000 participants attended Pink Dot in 2015.

In Singapore, demonstrations are not allowed to be held without a permit.

The new rules subject organisers and foreign participants to penalties of up to a SGD $10,000 ($7,127) fine, or jail of up to 6 months, or both.

"This is something we do not wish on you, or any of the organisers of Pink Dot," they said in a statement. "We acknowledge that this directly impacts and separates individuals with partners, friends and family who might not be Singapore citizens or permanent residents and we are just as upset by this."

The rule change is yet another blow to the rally's organisers, who were barred from receiving sponsorships by foreign entities like Google, Facebook and Twitter in August last year.

Since then, over 100 local sponsors have raised SGD $201,000 ($143,285) in support of Pink Dot, surpassing organisers' expectations.

Already, some locals have said they'd go to the rally, and are encouraging others to attend:

May want to go for Pink Dot this year just to make up for the numbers now that foreigners are not allowed to attend — ILKJ (@IanLeong93) May 14, 2017

Mashable has reached out to Pink Dot for comment.