Michael Jackson has become a father again, according to US news reports, but mystery remains as to whether the six-month boy was adopted or is the popstar's biological offspring.

There is speculation the mother is Jackson's ex-wife

The existence of the child was discovered after Jackson introduced him to magicians Siegfried and Roy while visiting them backstage after one of their performances in Las Vegas, Nevada, US magazine People reported.

The magazine also quoted a source as saying that the boy had not been adopted, and there has been speculation that Jackson's ex-wife, nurse Debbie Rowe, may be the mother.

A spokesman for Jackson's publicist said that they would not comment on the singer's personal life.

Complicated love-life

Rowe bore Jackson two children during their marriage, son Prince Michael, now five years old and daughter Paris, now four years old, before divorcing him in 1999.

However the couple are still said to be close, and Jackson's new son even shares his brother's name, being called Prince Michael II.

Music producer Gary Pudney told the magazine that Jackson wanted several children because he himself had had such "a lonely childhood".

"His motivation in having children is partly because of that but mainly because he loves them. Now he has three beautiful children," he said.

Jackson was also married to Elvis Presley's daughter Lisa Marie for 18 months before splitting up with her in 1996.

She went on to marry Hollywood actor Nicolas Cage last week.