Sir Elton John is reportedly planning to have another baby.

The music legend and his long-term partner David Furnish are already parents to 14-month-old son Zachary.

It has been claimed that Elton is keen for the newest addition to have a different biological father to Zachary, so both he and David will be blood fathers.

"The wheels are in motion. David and Elton have never hidden their desire to extend their family, and believe the time is right for another child. By the end of this year, or the beginning of next year, there will be a fourth member of the John-Furnish clan," a source told British newspaper The Mirror.

"They are incredibly excited and loving every minute of parenthood."

The couple tied the knot in a civil partnership in 2005. Zachary was born to a surrogate mother in California on Christmas Day 2010.

David gushed about the couple's baby at the time.

"For many years we have talked about fulfilling one of our greatest wishes by becoming parents. And now this wish has been granted to us, we feel so blessed and lucky," he said.

At the time of Zachary's birth it was reported that Elton had been recorded as the tot's father at the local register office in Los Angeles - although both parties insist they don't know which one of them is Zachary's biological dad.

Both claim they "contributed" to the process.

"For the time being we don't have a clue who the biological father is. We look at him every day and at the moment he has Elton's nose and my hands," David said.

A spokesperson for Elton refused to comment on the family reports last night.