People dressed up as US President Donald Trump and North Korean leader Kim Jong Un caused a commotion when they appeared in the stands at the Olympic Games Opening Ceremony on Friday before swiftly being shown out by security staff.

"We're getting along great," said the Kim lookalike, who declined to give his name.

"We wanted to surprise everyone and bring world peace and then we're being escorted out by security guards, which I think is really unfair," he added. "Doesn't everyone want peace?"

The ceremony was marked by a show of unity between North and South Korea.

Athletes from both countries entered the arena under a flag depicting a unified Korea as American Vice President Mike Pence and Kim's sister, Kim Yo Jong, watched on from a VIP box.

"Is my sister getting the same treatment?," the Kim lookalike said as he was escorted out of the stadium.