Beyonce and Lady Gaga have hinted at a new collaboration.

The pair - who appeared together on 2009 hit "Telephone" and extended version "Video Phone" - have fueled rumors they have returned to the studio by posting pictures of them wearing similar earrings. In November, Gaga posted a photograph on Instagram of a pair of earrings engraved with the word "Ratchet," while in December, Beyonce posted two photos of similar pieces of jewelry. On December 29, Beyonce posted a photo of the bamboo earrings alongside a pair of purple printed flat shoes, and followed it up the next day with another image of herself wearing the earrings.

It is thought they refer to a track called "Ratchet," which is also set to include rapper Azealia Banks, and may be released later this month as the lead single from Gaga's new album, ARTPOP.

"I worked with Lady Gaga, but I worked with Lady Gaga from afar. We worked via email and via Internet. We have a song called 'Red Flame' and a song called 'Ratchet,' but I don't know what she's doing with it. She's going to release it when she wants to release it," Azealia said in September.

In October, Gaga confirmed plans to record with Beyonce again. Asked in a Twitter chat if ARTPOP would feature a sequel to "Telephone," she replied, "Fact."