WELLINGTON - New Zealand Prime Minister John Key on Tuesday congratulated Prince William and his wife Catherine on the birth of the baby boy, and the country marked the arrival of the third in line to the head of state with a 21-gun salute in the earthquake-shaken capital of Wellington.

"The birth of a child is a time of great joy and excitement, and I know they will make excellent parents," Key said in a statement.

Key also extended his congratulations to the Prince of Wales and Duchess of Cornwall, and the Queen and Prince Phillip, on the arrival of the newest member of the royal family.

New Zealand's official gift to the royal couple was a hand-spun, hand-knitted fine lace shawl, similar to the one that New Zealand gave when Prince William was born in 1982.

An invitation was sent to knitters around the country to knit baby vests to give to new parents at local maternity and neonatal units on the couple's behalf.

Wellington Mayor Celia Wade-Brown said the city, which is recovering from two large quakes on Sunday and a series of aftershocks, welcomed the warning of the 21-gun salute.

"Given that quite a lot of people are jumpy after the quakes of the past few days, we appreciate the warning," Wade-Brown said in a statement.