China's performance in badminton deteriorated in the Rio Olympics compared to the London Olympics four years ago, said Youth and Sports Minister Khairy Jamaluddin.

He said this when asked about China national badminton head coach Li Yongbo's remark that Malaysia's Lee Chong Wei would possibly be a world champion if the badminton ace had trained with his team.

"I don't want to comment on what he (Li) said because it's all very speculative.

"I don't know what he meant by that but I think we know that China's own performance also deteriorated because it was a clean sweep in London 2012 for China," the minister told reporters at the Kuala Lumpur International Airport today.

Khairy was attending the welcoming reception for the Olympians returning from Rio.

Khairy also pointed out the differences in the semi-finals matches played by Lee and Chen.

Lee played three sets against China's Lin Dan, with the third set being a very close and intense match, while Chen played straight sets against Denmark's Viktor Axelsen, he said.

Besides, Chen is 26 years old while Lee is already 34.

"And it was just a one-day rest (before the finals). I think it took a lot out of Chong Wei.

"He gave his best but Chen was just better on that day," Khairy said.

Lee played against Chen in the closely-fought badminton men's singles final at the Rio Olympics last Saturday.

He was ultimately defeated, making this his third Olympic silver.

The Malaysian had said that this would be his final Olympics outing.