Prince Harry and Meghan Markle have sent thank you cards to fans who wrote to congratulate them on their engagement.

Prince Harry and Meghan Markle

Prince Harry and Meghan Markle

The couple admitted they were "incredibly touched" by people who penned letters to them after they got engaged in November 2017, and "greatly appreciated" the correspondence ahead of their May 19 wedding at St George's Chapel, Windsor.

An Instagram user posted a picture of the card, which featured the pair on the front and a message inside which read: "Prince Harry and Ms. Meghan Markle were incredibly touched that you took the trouble to write as you did in connection to their forthcoming Wedding.

"It really was most thoughtful of you and greatly appreciated. His Royal Highness and Ms. Markle send you their warmest thanks and very best wishes. (sic)"

The format of the card and message inside sparked comparisons to one sent by Duchess Catherine in February last year when she thanked fans for writing to her on her 35th birthday in January 2017.

The message read: "The Duchess of Cambridge was touched that you took the trouble to write as you did on the occasion of her birthday.

"It really was most thoughtful of you and Her Royal Highness sends you her warmest thanks and best wishes."

Last month, Harry, 33, and Meghan, 36, thanked their fans for their "generous messages" following the release of the pair's engagement photos.

Alongside another picture, they said in a statement: "Thank you so much for all of the wonderful comments following the release of Prince Harry and Ms Meghan Markle's engagement photographs.

"The couple are so grateful for the warm and generous messages they have received during such a happy time in their lives.

"As a way to say thank you, they have decided to share this candid photograph from the day of their portrait sittings directly with all of you."