Soviet dissident Yelena Bonner, the widow of Nobel Peace Prize winner Andrei Sakharov and tireless critic of Vladimir Putin, has died aged 88 in her adopted home in the United States.

A pediatrician by training but a historic figure in life, Ms Bonner died on Saturday in Boston after undergoing heart surgery for a third time, her friend and fellow rights activist Lyudmila Alexeyeva said.

After a suburban Boston ceremony, Ms Bonner’s ashes will be interred next to her husband’s remains at Moscow’s Vostryakovo Cemetery, her daughter said in a statement released yesterday.

A seminal figure in the rights movement, Ms Bonner was remembered as an unbowed fighter for Soviet freedoms who became so disillusioned with the course taken by modern Russia that she spent her last years in the United States.

“I am still stunned that our youth do not remember who Sakharov is. Unfortunately, Bonner is even less known. It is sad, but she is not the figure here that she is in the United States,” said the Moscow-based Alexeyeva.

There was no immediate reaction from President Dmitry Medvedev or his predecessor and current Premier Putin, an ex-KGB man whose resignation Ms Bonner demanded in a 2010 open letter titled simply “Putin Must Go”.