Putin is due to visit China in early September for celebrations marking the 80th anniversary of the end of World War II.

"If it so happens that in the end the US president decides to visit China during those days, then of course such a meeting cannot in theory be excluded," Kremlin spokesman Dmitry Peskov told reporters including AFP at a briefing.

Chinese troops will parade through Beijing's Tiananmen Square alongside aircraft flypasts and high-tech weaponry to mark the anniversary on September 3, Chinese officials said last month.

Millions of Chinese people were killed during a prolonged war with imperial Japan in the 1930s and 40s, which merged with the global conflagration following Tokyo's attack on Pearl Harbor in 1941.

The war ended with Japan's surrender.

Beijing's Communist Party has held a series of blockbuster events in recent years to commemorate its wartime resistance, vowing that China will never be brought to its knees in such a way again.

The Kremlin has confirmed Putin will attend the celebrations and Chinese officials said other world leaders are also expected.