William, who is commissioned in all three of Britain's armed services, was expected to wear a military uniform as is traditional at royal weddings - AP (File Photo)

LONDON: Prince William will wear the red uniform of Colonel of the Irish Guards when he marries girlfriend Kate Middleton on Friday, royal officials said.

William, who is commissioned in all three of Britain's armed services, was expected to wear a military uniform as is traditional at royal weddings and was appointed as Colonel of the Irish Guards in February.

His father, heir-to-the-throne Prince Charles chose Royal Navy attire for his wedding to Princess Diana. The Irish Guards are an Army infantry regiment.

William's office said the prince, who is currently a helicopter pilot with the Royal Air Force's search and rescue team, would wear an “Irish Guards Mounted Officer's uniform in Guard of Honour Order with a Forage Cap”.

The red tunic features the Irish Guards' arrangement of buttons in groups of four and William will wear a gold and crimson sash and gold sword slings, although he will not carry a sword.

Details of Middleton's wedding dress will remain a closely guarded secret until she makes her appearance at London's Westminster Abbey for the service shortly before 10:00 GMT.

William's younger brother and best man will wear an officer's uniform of the Blues and Royals regiment of the Household Cavalry, while Prince Charles, who has held the rank of admiral since 2006, will wear a naval uniform.

Royal officials have also given details about Middleton's wedding ring.

Family jewellers Wartski, who made the wedding rings of Charles and his second wife Camilla, have fashioned the ring from Welsh gold given to William by Queen Elizabeth shortly after his engagement was announced.

Harry, as best man, will have the responsibility of carrying the ring to Westminster Abbey for the wedding service.