Lisa Marie Presley is pregnant with twins, it has been claimed.

The 40-year-old star - who is expecting her first child with music producer husband Michael Lockwood - recently discovered her double joy and that one of the babies is a boy.

A source is quoted by America's Star magazine as saying: "Michael told me that he and Lisa have been trying to get pregnant for about a year. He also said that they had a sonogram two weeks ago, and one baby opened its legs, and they saw something! Michael was beaming."

Lisa Marie - the daughter of late music legend Elvis Presley - is believed to be around four-and-a-half-months pregnant.

She already has two children, 18-year-old daughter Danielle and son Benjamin, 15, from her first marriage to musician Danny Keough, which ended in 1994.

Meanwhile, Lisa Marie's mother Priscilla has revealed she can't wait to meet her new grandchildren.

She beamed to OK! magazine: "We are all excited. All of our kids are grown up, so this is really exciting news for all of us."

Priscilla - who is set to be a contestant on the sixth series of hit TV show 'Dancing with the Stars' later this month - also hit out at recent speculation about Lisa Marie's weight gain.

She said: "I think it's cruel what's happening today with people and with celebrities. You want to be a perfectionist and do the best you possibly can and you have parasites out there trying to bring you down. It's a very tough time for people in the limelight today."

Priscilla's six-year marriage to Elvis ended in divorce in 1973.