The Home Alone film star is said to have donated sperm to help Jacko create his seven-year-old offspring - real name Prince Michael II - with an unknown surrogate mum.

The two celebrities became firm friends after Culkin, now 29, shot to fame as a child in the 1990 box office smash.

He went on to star alongside Jackson in the video for his hit song Black or White in 1991, regularly visited the singer's Neverland ranch, and took the witness stand to defend him at his 2005 child molestation trial.

One source said: "It is well known Jackson and Macaulay shared a unique bond.

"Now rumours are spreading like wildfire that Macaulay, who Jackson nicknamed Mack, is actually Blanket's biological dad."

Source