Monaco: Monaco`s father-to-be Prince Albert II said the principality`s newest royals were likely to make an appearance before Christmas, adding he had asked his South African wife Princess Charlene to keep him in the dark about the twins` gender.
Albert already has two children from out-of-wedlock affairs, which rules them out of the succession.
He told Monaco-Matin daily in an interview published on Wednesday that the twins were due "around Christmas".
"But as it is a twin pregnancy the birth will surely take place a dozen days early," he added.
Albert said the princess was doing "very well" as she heads into the final stretch of the pregnancy, and was keeping mum on the babies` sex as he had requested.
"The princess probably knows but she is playing the game. She is keeping the secret as I asked her to," he told the newspaper.
"You know, one doesn`t often have the opportunity to have such pleasant surprises in life, that is why I prefer not to know the babies` gender before the birth."
Charlene, 36, a Zimbabwe-born former Olympic swimmer, married 56-year-old Albert in 2011 despite a storm of rumours their relationship was on the verge of collapse.
Media reports suggested she had attempted to flee Monaco just days before their wedding.
It was also widely reported that the couple spent at least part of their honeymoon in separate hotels. A steady stream of pictures of the princess looking gloomy continued to fuel reports she was depressed.
A first-time mother, the glamorous blonde`s twins replace Albert`s sister Caroline as the next in line to the Monaco throne, and will be the grandsons or granddaughters of Hollywood superstar Grace Kelly.
Albert said that as they were twins, it would be the first born who would succeed him.
"In the case that one is a girl and the other a boy, it will be the boy."
Albert succeeded his father, Kelly`s husband Prince Rainer, in 2005.
He had a daughter, Jazmin, after a fling with former waitress Tamara Rotolo. He denied being her father for years before DNA tests proved otherwise when she was a teenager.
The prince also has a younger son, Alexandre Coste, from an affair with Nicole Coste, a former Air France hostess.
Under Monaco`s inheritance laws, neither of the two children have any claim to royal titles or to be considered as heirs to Albert because they were born outside a marriage.
They do however have legal rights to a share of his huge personal fortune, estimated by Forbes magazine to exceed one billion dollars.