Image caption The couple said they were overwhelmed with happiness at news of the birth

Sir Elton John and his partner David Furnish have become parents to a son born to a surrogate mother in California.

Zachary Jackson Levon Furnish-John was born on Christmas Day, the UK musician and Canadian filmmaker told the Usmagazine.com website.

"Zachary is healthy and doing really well, and we are very proud and happy parents," said the couple.

They provided no details about the surrogacy arrangement.

"We are overwhelmed with happiness and joy at this very special moment," the couple told the website in a statement.

They said the boy weighed 7lb15oz (3.6kg).

Surrogacy and gay parents The UK has strict regulations in place for anyone considering surrogacy, so sometimes couples consider going overseas to countries where it is easier to complete the process

Barrie and Tony Drewitt-Barlow, became Britain's first gay surrogate parents in 1999

In April 2010, changes to the law meant that for the first time in British history, two men could be named as parents on a child's birth certificate

In the UK, the child's birth mother is always considered the legal parent unless this is changed by a parental order made by a court

The US state of California is recognised as somewhere where surrogacy agreements - including those made by gay and lesbian couples - are generally accepted under law

Other gay celebrities who have used a surrogate to have children this year include actor Neil Patrick Harris and his partner David Burtka

A representative for the couple said they intended to protect and respect the privacy of the surrogate mother, and would not be discussing any details relating to the surrogacy arrangements.

Close friend of the couple, actress and model Elizabeth Hurley, offered her best wishes.

"Massive congratulations to David and Elton on having their beautiful son. Can't wait for my first cuddle," she wrote on the micro-blogging site Twitter.

Whilst presenter Piers Morgan, who recently interviewed Sir Elton during his Life Stories series, joked on his Twitter page: "Feel such a fool - Sir Elton never even hinted he was pregnant during our interview."

Sex And The City star Sarah Jessica Parker and her actor husband Matthew Broderick had twin girls by a surrogate mother in June last year and in 2008, pop star Ricky Martin also used a surrogate to have twin boys.

Sir Elton and former advertising executive Mr Furnish met in 1993 and were joined in a civil ceremony in 2005.

Last year the couple tried to adopt a 14-month-old HIV positive boy from Ukraine named Lev.

However, Ukrainian officials said Sir Elton, 63, was too old and his civil partnership with Mr Furnish, 48, would not be recognised as a marriage by Kiev.

In December, Mr Furnish told the BBC that they were working to ensure Lev and his brother "have the best health care, education and family options available to them".

Sir Elton released his 30th studio album in October this year.