Chinese women are using iPhone 6s to prove they have skinny legs on social media

The trend is the latest in a series of extreme social media 'beauty' challenges

The 'iPhone knees' challenge has been circulating on social media (Weibo)

Women in China are using iPhones to demonstrate how thin they are.

Photos have been posted on social media of the devices covering the knees of women in ‘selfies’ which demonstrate their skinny legs.

The trend follows the similar ‘A4 waist’ craze, where women on social network Weibo posted pictures of themselves with a sheet of paper covering their slim torsos, leading to an international outcry over beauty standards.

An iPhone 6 measures just 13.8 centimetres in length.

The trend has caused widespread discussion in China, where nearly two million users have read a thread on the topic.

“The pressure for women to conform to a thinness ideal pervades all parts of the developed world and China is no exception to the rule,” Lisa Moore, Research and Advocacy manager at the Women’s Foundation, told the South China Morning Post.

“Media has played a significant role in transmitting thinness norms and values, which has shown links to increased body image dissatisfaction, eating disorders and lowered self-esteem among women.

“We are concerned with the ways that unrealistic and unattainable beauty standards are directly affecting women and girl’s sense of self-worth.”

However, despite its popularity, other Weibo users criticised the trend and said it is "the worst one yet".

Another comments said: “There's brain damage everywhere. Why is it good to be thin? Something's amiss.”

“I liked all the comments that said this is an illness,” said another user.

Some even went as far as posting picture with larger devices, such as iPads, over their knees in protest.

Other Chinese social media ‘beauty’ trends include people posting pictures of coins lined up on their collar bones and touching their belly buttons with an arm wrapped around their back.