Just weeks ago Beyoncé paid homage to Michelle Obama in an open letter and now she has showered the first lady in her life with praise.

To mark Mother's Day in the United States, the 30-year-old singer declared her appreciation and love for her mother, Tina Knowles, in an open letter on Tumblr in which she thanked her for "all the sacrifices" that she made on her behalf.

In the letter, titled Dear Mama, she said that her mother helped her grow as a person and that she would be nowhere without her.

She wrote: "Everything I am is because of you. You are the first voice that ever sang to me. At every turn you push me to be better. You teach me to be true to myself and the ones I love."

The Countdown singer, who gave birth to her own daughter Blue Ivy in January, went on to reveal that it was becoming a mother herself that made her realise just how great a role model Tina is as a parent.

"When I look into your eyes, I am sooo proud. Now that I'm a mother, I truly realise all the sacrifices you made for us," she said.

The heartfelt note concluded with Beyoncé telling her mother how much she loves her. "My love for you goes beyond what I can say. Happy Happy Mamas Day. Love, Beyoncé."

Beyoncé joined a host of celebrities, including Angela Simmons and Mariah Carey, who took to the internet to thank the special women in their lives.