Michelle Obama's memoir breaks sales record in 15 days

Former First Lady Michelle Obama's memoir Becoming has become the best-selling book released this year in the US just 15 days after publication.

It has sold more than two million copies in the US and Canada, BBC News reports, citingn NPD BookScan data.

The sales figures were announced by Penguin Random House on Friday.

The publisher said the book is also a bestseller in many other countries including Australia, the UK, France, Germany, Korea and South Africa.

The book is a window into the personal life of the Obamas prior to, throughout, and following their time at the White House as the first African-American first lady and the first black US President Barack Obama.

In it, Mrs Obama reveals difficulties in her marriage with Barack, disclosing details of how the couple suffered a miscarriage and later used in vitro fertilisation (IVF) to conceive both children, Malia and Sasha.