Singer Britney Spears has dropped her single "Mood ring", which originally featured as a bonus track on her 2016 album "Glory". It had only released in Japan.

Marking her first musical release in four years, Spears was excited to announce that the song was now available to stream everywhere and shared a snippet of "Mood ring" on Instagram, reports eonline.com.

"Repurposed this since we didn't use it...," she wrote. "You folks wanted a new album cover ….. ta da there you go!!!! What was requested next is out now….. I hope you turn #MoodRing up sooooooo loud!!!!"

"Mood ring" sees Spears embracing her inner self as she opens up to her new love, who brings out all the colours on her "mood ring".

Ahead of the re-release, Spears surprised fans with new "Glory" cover art to celebrate the album reaching no. 1 on iTunes.

In it, she can be seen wearing a gold chainmail bodysuit as she holds a thick chain in the middle of the desert.

"You asked for a new Glory cover and since it went to number one we had to make it happen !!!!" she posted. "Couldn't have done it without you all!!!!"