OnePlus could be set to launch a new variation of its flagship smartphone, OnePlus 5T, later this month, according to a new video shared by the company.

Last week, the Chinese smartphone manufacturer published a short teaser trailer on YouTube showing people handling a mysterious object hidden inside a OnePlus branded box.

“We took to the streets of London to recapture an unforgettable feeling!,” the video caption mysteriously teases.

“Can you guess what's coming?”

The video shows people describing the object hidden in the box, offering a few clues about the upcoming product.

“Kinda smooth but also like a little bit textured,” one person says while handling the hidden OnePlus device.

Another adds: “I like the texture, it’s very grippy.”

But the biggest clue comes courtesy of a gentleman who says, “it’s a bit reminiscent of the Sandstone covers they used to have.”

Another OnePlus fan says the mysterious new item “feels like the original one”.

Based on these comments, the most popular theory is that OnePlus will launch a new Sandstone version of its new flagship, OnePlus 5T.

The manufacturer’s first handset, OnePlus One, had a textured sandstone rear cover, which helped it stand-out from the swathes of polished aluminium smartphones.

Whatever is hidden inside the box, OnePlus suggests we’ll find out before the month is out.

The minute-long teaser trailer ends with the words: “Unbox The Mystery. January 2018.”

OnePlus already sells a sandstone-style case for its OnePlus 5 and OnePlus 5T handsets, so the video certainly isn’t pointing towards a new case.

However, it is possible the company will launch a new sandstone variant of the phone.

In the past, OnePlus has released new colours for its flagship smartphone in the months following the launch of a new handset.

For example, OnePlus launched a new Soft Gold colour for its OnePlus 5 handset two months after it was first announced.

OnePlus 5T was announced on November 16th of this year.

The flagship handset is an incremental upgrade on its predecessor, OnePlus 5.

It features an expansive 6.01-inch 1080p display – squeezed into the same physical footprint as the OnePlus 5, which had a 5.5-inch screen.

Elsewhere, it also introduced a new dual camera system, as well as facial recognition technology.

OnePlus 5T is powered by Qualcomm’s top-of-the-line Snapdragon 835 chipset with either 6GB or 8GB of RAM, 64GB or 128GB of storage.

It starts at £449 for the entry-level model, rising to the £499 for the maxed-out model.