Pop superstar Taylor Swift has revealed that her mother Andrea Finlay is suffering from cancer.

The 25-year-old singer confirmed the devastating diagnosis in an emotional post published on her Tumblr page, telling fans that she prayed that they would never "get news like this".

"I'm writing to you with an update I wish I wasn't giving you, but it's important and I'm used to sharing important events in my life with you ... This is something my family and I thought you should know about now," she wrote.

In the open letter, Swift explained that she had urged her mother to get a health screening for Christmas to ease some of her concerns.

"The results came in, and I'm saddened to tell you that my mom has been diagnosed with cancer," she explained.

Swift revealed that her mother, who has been her biggest supporter since she catapulted to fame, was keen to raise awareness while battling the disease.

"I'd like to keep the details of her condition and treatment plans private, but she wanted you to know. She wanted you to know because your parents may be too busy juggling everything they've got going on to go to the doctor, and maybe you reminding them to go get checked for cancer could possibly lead to an early diagnosis and an easier battle."

She added: "She wanted you to know why she may not be at as many shows this tour. She's got an important battle to fight."

Swift signed off the note by thanking her fans, affectionately known as the 'Swifties', for their continued support.

"Thank you for caring about my family so much that she would want me to share this information with you," she said