The 75-year-old monarch is currently undergoing treatment for an undisclosed form of cancer. It will be the king's first significant public appearance since he announced his diagnosis in February.
The Palace also confirmed his daughter-in-law Catherine, Princess of Wales and her husband Prince William will not be in attendance following her shock cancer announcement at the end of last week. She said: "I wanted to take this opportunity to say thank you personally, for all the wonderful messages of support and for your understanding while I've been recovering"