Olivia Newton-John was so secretive about her wedding to millionaire John Easterling that her daughter did not know until a couple of days before the nuptials in Peru.

Newton-John and Easterling also were secretly engaged for six months before telling family and friends.

The revelations came as Newton-John broke her silence in interviews with news organisations in Britain and the US.

"I'm so happy and so fortunate to have met a wonderful man," the Australian singer and actress said in an interview on US morning TV talkshow Today.

"I'm just very lucky."

Newton-John, the star of the hit musical Grease, and Amazon herb entrepreneur Easterling were married last month in two secret ceremonies.

The first was on June 21 on a mountaintop in Peru.

Instead of a traditional white wedding gown, Newton-John, 59, wore a traditional Peruvian matrimonial manta.

Easterling, 56, ditched a tuxedo for a poncho.

The ceremony was conducted in the ancient language of Quechua.

The couple had known each other for 15 years, but fell in love 18 months ago on a trip to South America.

"Suddenly in the peace of the jungle, away from the city noise and distractions, we just knew we were meant to be together," Newton-John said in an interview with Britain's Hello! magazine, which includes photos of both weddings.

The newlyweds honeymooned in Peru for a week and then travelled to Easterling's home in the millionaire's haven of Jupiter Island, Florida for a beach wedding that made the nuptials legal.

Newton-John explained in her Hello! interview why the couple was engaged six months ago and kept it secret from family and friends, including her 22-year-old daughter Chloe.

"Much of our lives have been lived out in public and we wanted to keep our relationship very private," she said.

"It was precious to us, something we wanted to share with each other and enjoy without being chatted about.

"It's the reason we kept our two ceremonies secret.

"Even Chloe did not know until a couple of days before we went to Peru that John and I were to be married."

Easterling, the chief executive of a herbal wellness company, Amazon Herb Company, said he did not want a big, public wedding.

"We didn't need a big song and dance celebration of our union," he told Hello!

"For me, every day is a celebration and the rest of our lives will be a honeymoon."

Close family and friends did not learn about the two weddings until the couple held a July 4 barbecue at Newton-John's Malibu mansion.

Newton-John used her Today interview to plug her new CD, A Celebration of Song, a compilation of duets with artists including Jimmy Barnes, Delta Goodrem, Keith Urban, Cliff Richard, Richard Marx, Amy Sky and Barry Gibb.

Newton-John told the huge American TV audience how the album's proceeds would be donated to the Olivia Newton-John Cancer and Wellness Centre in Melbourne.

Newton-John was diagnosed with breast cancer in 1992 and successfully fought the disease.