Four Xiaomi smartphones, including the Mi 11 Ultra, Mi 11 Pro and expected foldable handset, the Mi Mix 4, have been spotted in a listing posted by China's 3C certification website.

Consumer electronics require this step before being able to go on sale in the country, so it's generally a sign that they are imminent.

The phones have appeared under the identifiers M2102K1C, M2102K1AC, M2011J18C and M2103K19C, with the latter a currently unknown Xiaomi model.

The most interesting information to be gleaned from the listing is that the Mi 11 Ultra, Pro and Mi Mix 4 will each feature 67.1W fast charging. The mystery handset will sport 22.5W charging.

Previous rumours have suggested the Ultra will feature a 6.81-inch 2560 x 1440 AMOLED display with a 120Hz refresh rate.

It is also said to come with a triple-lens camera system.

The Mi Mix 4 will reportedly have an outward folding display. It might also be called the Mi Mi 4 Pro Max - a rather long-winded name that has popped up in recent rumours.

The conventional Xiaomi Mi 11 has already been launched globally and is "packed with potential", as we say in our in-depth review.

We'll bring you more on the other handsets as we have it.