Britain's Prince William and his wife Kate, Duchess of Cambridge Picture: Kirsty Wigglesworth/AP

London - Britain's Prince William and his wife Kate are expecting a third child, their office said on Monday.

"The Duke and Duchess of Cambridge are very pleased to announce that The Duchess of Cambridge is expecting their third child," Kensington Palace said in a statement. 

Officials say Kate is suffering from Hyperemesis Gravidarum, a form of severe morning sickness, and will not carry out her engagements on Monday.

William and Kate already have two children, Prince George and Princess Charlotte.

Reuters and AP