(Cover) - EN Showbiz - Denmarks Crown Prince Frederik has joked he will call either his new son or daughter Elvis, after his wife Crown Princess Mary gave birth to twins yesterday.

The royal couple confirmed they were expecting two children in August, following weeks of speculation. They are already parents to Christian, five, and three-year-old Isabella.

Over the festive period it was reported Mary was close to giving birth, and yesterday the royal court confirmed she had welcomed the twins at the national Rigshospitalet hospital in Copenhagen.

[Mary is the mother of] two fine children, a statement said. Both mother and children are doing well.

Mary went into hospital early on Saturday morning, and Frederik was with her throughout the labour.

It's a miracle, he said. It's two small hearts to keep an eye on.

Names have not been decided upon yet, with the prince joking: The names we are still talking about, and I've just been told that he was born on Elvis [Presleys] birthday - then one of them we'll call Elvis so far.

The couples son weighed 5lbs. 14oz. and was born first, while his sister came along 26 minutes later weighing 5lbs. 10oz. The boy measured 47cm and the girl 46cm.

Mary who is from Tasmania and Frederik married in May 2004. (C) Cover Media