Madonna's son just viciously insulted her on Instagram.

Madonna‘s son 15-year-old son, Rocco Ritchie, has continued to add to the vicious custody battle by implying his mother is a “bitch”.

It is alleged Ritchie set up an Instagram account, where in the biographical details it simply writes, “Son Of A Bitch”.

The Daily Mail reports that Ritchie shut down his social media in January after Madonna shared a photo of the two together, so this is the first time he has posted for months.

Ritchie's Instagram account.

The account is public, as is the description, however his posts are private. Speculation exists about whether the account actually is Ritchie's, although, all of the profile images updated so far have been close-up, private ones of his face.

Some say the description is closely linked to one of Madonna's meltdowns she had during shows in Australia, where she called Ritchie a "son of a bitch".

Madonna has not seen her son since Christmas last year, however, is hoping to reunite with him on Tuesday in the United Kingdom.

Ritchie didn't come back after spending Christmas in New York with his father and has continued to avoid her since. The two were allegedly meant to see one another at Easter time, but Ritchie flew to the Maldives to be with his father.

I miss this boy so full of life so full@of@love????! I hope we see that Leo Sun soon. The light is blinding!

A photo posted by Madonna (@madonna) on Feb 21, 2016 at 10:34pm PST

Guy Ritchie and Madonna have been locked in an extremely bitter and public custody for their son for over fourth months.

Sources claim Madonna has been left deeply upset over Ritchie's Instagram account, and a further testament to why she needs to reunite with her son.

A source told the Daily Mail, "The fact it [the Instagram account] has been set up at all, even if it is just a prank by one of his friends, shows how public their feud has become. For Madonna, it is proof their relationship needs to get back on track as soon as possible."

Madonna has not commented on the incident.

Watch the moment brave women admit the first moment they felt like a "terrible mother".