WELLINGTON, Dec. 4 (Xinhua) -- New Zealand Prime Minister John Key on Tuesday congratulated British royals Prince William and his wife Catherine, Duchess of Cambridge on the news that they are expecting a baby.

Prince William is second in line to the throne after his father Prince Charles, and is set to be New Zealand's future head of state.

"On behalf of the people of New Zealand, I congratulate them both," Key said in a statement.

He said he knew the Queen and Prince Phillip, Prince William's grandparents, would be extremely pleased.

"It is an important day in any young couple's life when a baby is expected and I know that Catherine and William will be as nervous and excited as anyone," he said.

"We wish them both the very best and hope Catherine's stay in hospital is a short one."