Macaulay Culkin and Michael Jackson were long known to have shared some kind of special relationship. Now it is claimed that the former child actor is the mystery father of Jackson's youngest son, Blanket.

Culkin is said to have donated sperm to help Jackson create the 7-year-old, whose real name is Prince Michael II, with an unknown surrogate moter. The two became good friends after Culkin shot to fame as a child actor in the 1990 smash hit "Home Alone."

Once 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."

Close friends of Jackson say that he was not the natural father of any of his three children. Blanket also has two older siblings, - Michael, 12, and Paris, 11. Speculation heated up after repeated claims that a "well-known Hollywood actor" donated sperm for Blanket.

Sources now reveal that the actor was Culkin, who they say Michael asked to donate sperm to complete his "perfect" family. The source added:

"This isn't just chitter-chatter, even Culkin suspects he's Blanket's father.

"So many names have been mentioned as prospective dads, and this is probably the wackiest yet.

"But Jackson and Culkin were best friends. He was one of the few people Jackson really trusted and Mack never let him down.

"Really, Jackson idolised him - that's why he asked Mack to donate sperm.

"Deep down, I think he always wished Mack was his son. Creating Blanket was the next best thing."

Culkin is also the godfather to Jackson's two other children. He has told friends that he will not comment in public out of loyalty to his late friend.

As for Jackson's other two kids, is dermatologist Dr. Arnold Klein, was said to have donated sperm that created them. British actor Mark Lester has also claimed that he donated sperm and believes he is Paris' father.