The National Day Rally on Sunday (Aug 21) has been suspended after Prime Minister Lee Hsien Loong was taken ill.
The medical team attending to him assessed that his condition is not serious.
Mr Lee was in the midst of delivering his English speech when the rally was stopped at around 9.20pm.
A statement subsequently said that Mr Lee would resume his rally later.
"PM Lee says please enjoy the reception," Deputy Prime Minister Teo Chee Hean told the audience. He added that Mr Lee will resume his speech later, to applause from the audience.
Speaking to the media, DPM Tharman Shanmugaratnam said Mr Lee is feeling fine and he is taking a rest.
Mr Lee, who has had a tough schedule, has been working very hard, he said.
But he is "in good shape" and "he is strong enough to carry on", DPM Tharman added.
In an update on Mr Lee's Twitter account at 10.22pm, the Prime Minister's Office said he had been feeling unsteady because of "prolonged standing, heat and dehydration".
"His heart is fine and he did not have a stroke," the tweet added.
Mr Lee was seen waving at the audience before he walked off the stage with the help of Mr Teo, Defence Minister Ng Eng Hen and Acting Education Minister Ng Chee Meng.
Curtains were drawn and it was all silent in the ITE College Central auditorium.
In a statement on his Facebook page at 9.31pm, the Prime Minister's Office (PMO) said Mr Lee "took ill while speaking at National Day Rally".
"The medical team is attending to him right now. They assess that his condition is not serious. PMO will update in due course," the post added. (dan)
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