The executive assistant to one of Amazon's top Australian bosses says she was sacked for asking to work flexible hours so she could pick up her children from school while her husband was in hospital, and is now suing the e-commerce giant.

Rachel Shafner started work for Amazon in September 2017, and claims the world's second most valuable company assured her the role would be flexible to accommodate her looking after two young children.

Her parental duties increased in March 2018 when her husband became ill and required long stints in hospital, meaning Ms Shafner needed to pick up and drop off her children from school and day care.

In an application filed in the Federal Circuit Court in Melbourne, Ms Shafner said Amazon issued her a formal warning in late May for unexplained absences caused by her husband's illness.