Britney Spears will no longer perform alongside Madonna in Miami later this month, according to reports.

Spears was understood to have agreed to collaborate with the star during the final night of the US leg of Madonna's Sticky & Sweet world tour on November 26th.

However, Spears has reportedly cancelled the appearance after she was granted custody rights to see her two children, Jayden James, two, and Sean Preston, three, on the same day.

"Britney had always agreed to perform in Miami but her circumstances have changed over the past couple of months,” a source told the Sun newspaper.

"She and Kevin (Federline, ex-husband) are getting along fine now, Britney will have Jayden and Sean just before the holiday and Kevin will spend Thanksgiving day with them."

Federline currently has full custody over the pair's two children.

(by Jason Gregory)