The Vatican on Tuesday criticised the assisted suicide of Brittany Maynard, who took her life last weekend, aged 29.

Father Ignacio Carrasco de Paula, president of the Pontifical Academy for Life, described assisted suicide as an "absurdity" in an interview with Italian news agency ANSA.

"Society does not want to shoulder the cost of disease and this risks becoming the solution," he said.

"This woman [took her own life] thinking she would die with dignity, but this is the error, suicide is not a good thing, it is a bad thing because it is saying no to life and to everything it means with respect to our mission in the world and towards those around us."

The head of bioethics at the Vatican continued: "Brittany Maynard's gesture is in itself to be condemned, but what happened in her conscience is not for us to know."

"We always choose by seeking what is good, the problem is when we get it wrong," he added, arguing that if assisted suicide became the norm, terminally ill people would likely be "totally abandoned".

Maynard was diagnosed with a brain tumour on January 1 this year. She was later told that she had just six months to live, and decided to end her life before her illness became too debilitating.

She moved to Oregon, one of five states in the US where assisted dying is legal, and campaigned for dignity in dying in her last few months, becoming the face of advocacy organisation Compassion & Choices.

A spokesperson for the organisation confirmed her death on Saturday. "Brittany suffered increasingly frequent and longer seizures, severe head and neck pain, and stroke-like symptoms," a statement read.

"As symptoms grew more severe, she chose to abbreviate the dying process by taking the aid-in-dying medication she had received months ago. This choice is authorised under the Oregon Death With Dignity Act. She died as she intended – peacefully in her bedroom, in the arms of her loved ones."

"Goodbye to all my dear friends and family that I love. Today is the day I have chosen to pass away with dignity in the face of my terminal illness, this terrible brain cancer that has taken so much from me...but would have taken so much more," Maynard wrote on Facebook ahead of her death.

"The world is a beautiful place, travel has been my greatest teacher, my close friends and folks are the greatest givers. I even have a ring of support around my bed as I type...Goodbye world. Spread good energy. Pay it forward!"