Tourists have been treated to a natural phenomenon with a spinning ice circle forming in a partially frozen river in Hulunbuir, a city in north-eastern Inner Mongolia.

The ice discs form in slow moving water in cold climates. This one was formed in the Yimin River by a tributary that created a vortex like motion in the river.

The flow caused ice to form a perfectly circular rotating disc measuring approximately four metres in diameter.

Tourists came to watch the scene after local resident Zhao Guowen uploaded videos of the ice circle on the internet.

"When my swimming mates and I came here to take pictures of the ice a few days ago, we suddenly stumbled upon this natural scene, so we recorded some videos and uploaded them online," Mr Zhao said.

Some tourists dared to walk on the thin ice, posing and taking photos.

One swimmer braved temperatures as low as minus 20 degrees Celsius, diving off the disk and swimming against the icy current.

ABC/wires