Lee Hsien Loong [Photo: sina.com]

Singapore's Prime Minister Lee Hsien Loong went back on stage again on Sunday and the National Day Rally resumed.

"I gave everybody a scare. The last time I did this I was on the parade square in Safti, I fainted. I've never had so many doctors look at me all at once. They think I'm all right but I'm going to have a full check-up after this, " said Lee.

Lee suddenly took ill earlier while speaking at the rally. A medical team assessed that the prime minister's condition is not serious.

He was feeling unsteady because of prolonged standing, heat and dehydration and his heart is fine and he did not have a stroke, said the Prime Minister's Office (PMO) in an updated statement.

Singapore's Deputy Prime Minister and Coordinating Minister for Economic and Social Policies Tharman Shanmugaratnam blamed the tough schedule for his taking unwell.

"He's been having a very tough schedule, he’s been standing for some time so he's just feeling a little faint," Tharman said.