The student wrote her 475-page novel in less than two months

A 14-year-old schoolgirl has written a full-length science fiction novel in her spare time - without either her parents or teachers knowing.

Mia Foley Doyle, from Oxford, completed her 475-page book in a mere 50 days, after taking part in National Novel Writing Month.

The novel, called The Rebel Forces, is set 900 years in the future and tells of wars between Earth and other planets.

The pupil sometimes stayed up all night writing, despite also having homework to complete.

"My mum thought I was ill because I kept falling asleep," she told the Oxford Mail. "Before, I was doing it as a surprise, but now everyone knows it doesn't need to be a secret."

The teen's work was only discovered when a teacher at her school asked whether anyone had done anything "cool" lately, the local paper reported.

Doyle's school head Sue Croft said it was "very sophisticated, both in terms of the idea and also the quality of language and sophistication of vocabulary and writing."

"We knew she was gifted in English, but this was a real revelation."

The talented students is now hoping her story will be made available as an e-book.