Holocaust survivor Ruth Posner and her husband, Michael, both aged in their 90s, have died at a suicide clinic in Switzerland.

The Polish-born actress, 96, who escaped a Nazi ghetto as a child and forged a successful career in dance and drama, is thought to have died last weekend at the Pegasos clinic near Basel.

She and 97-year-old Michael sent an email to family and friends on Tuesday informing them of their decision to die, according to playwright Sonja Linden, who told BBC News she had received it.

In the note, first reported by The Times, the couple said they were "sorry not to have mentioned it, but when you receive this email, we will have shuffled off this mortal coil".

"The decision was mutual and without any outside pressure. We had lived a long life and together for almost 75 years. There came a point when failing senses, of sight and hearing and lack of energy was not living but existing that no care would improve," they wrote.

"We had an interesting and varied life, and except for the sorrow of losing Jeremy, our son. We enjoyed our time together, we tried not to regret the past, live in the present and not to expect too much from the future. Much love, Ruth & Mike".

Ms Linden, a close friend of Mrs Posner, paid tribute to her as "the most vibrant, amazing woman" and Mr Posner as a "remarkable, clever, intellectual man".

Speaking to the PA news agency, she said of Mrs Posner: "She felt increasingly, every time I visited her over the last year, she said 'we've had enough, we're ready to go, we don't want to just exist. And that's what we're doing, we're just existing at the moment."

Much of Mrs Posner's family was murdered in the Holocaust, including her parents, uncles, aunts and cousins - only she and one of her aunts survived.

The family were sent to the Radom Ghetto after the Nazis invaded Poland - but with the help of her father, Mrs Posner managed to escape onto the non-Jewish side, later hiding with a Catholic family. While living under a false identity, she was imprisoned as a Polish Catholic after the Warsaw Uprising of 1944.

She then managed to hide on a local farm near Essen until the end of World War Two, allowing her to flee to the UK aged 16.

She went on to become a member of the London Contemporary Dance Theatre and joined the Royal Shakespeare Company.

Mr Posner, a chemist, worked for the United Nations aid agency UNICEF, and after travelling the world, the couple settled in London. They lived in Belsize Park at the time of their deaths.

Ms Linden told PA that while she was "very sad" at the couple's deaths, she "completely endorses" their decision and understands why they took it.

She said Mrs Posner had been in favour of legalising assisted dying in England: "She wouldn't have had to make those arrangements, had to travel, she could've said goodbye more publicly."

Parliament is currently considering whether to change the law to allow assisted dying in England and Wales, which would apply to certain terminally ill patients reasonably expected to die within six months. Reports suggest neither of the Posners was terminally ill.

The Holocaust Memorial Trust paid tribute to Mrs Posner, describing her as "an extraordinary woman".

"Although then in her 80s, she made it her mission to speak to as many young people as possible about her experiences during the Holocaust. She hoped that the leaders of tomorrow would learn the lessons of the past," its chief executive Karen Pollock said in a statement.

"Ruth was one of a kind. Full of charisma and warmth, she left an impression on everyone she met. We will miss her."

The Campaign Against Antisemitism said she was influential in "educating future generations and never shying away from taking part in the fight against antisemitism".