The celebrated Russian cellist and conductor Mstislav Rostropovich has died at the age of 80.
Rostropovich was feted by Russia's President Vladimir Putin
A master musician, Mr Rostropovich was also renowned for his backing for human rights and opposition to Soviet rule.
He spent much of his career abroad, in self-imposed exile from the Soviet Union over his support for Nobel prize writer Alexander Solzhenitsyn.
But he returned as communism collapsed and performed a Bach suite as the Berlin Wall came down in 1989.
President Vladimir Putin said that his death was a "terrible loss" for Russian culture.
At Mr Rostropovich's 80th birthday celebrations a month ago, Mr Putin called the musician not only "a brilliant cellist and gifted conductor," but also "a firm defender of human rights".
He died at a Moscow clinic after a long illness, his spokeswoman said.
Reports from Russia said he would be buried in Moscow's Novodevichy cemetery, where his friend, the former President Boris Yeltsin, was laid to rest earlier this week.
Mr Rostropovich studied at the Moscow Conservatoire under composers such as Sergei Prokofiev and Dmitri Shostakovich, rapidly building a reputation for himself.
The cellist played Bach as the Berlin Wall came down
But his support for dissidents such as Mr Solzhenitsyn - declared in a letter to state-run newspaper Pravda in 1970 - made him a target for the Russian authorities.
He left the Soviet Union and spent several years in the West with his wife, soprano Galina Vishnevskaya, and their children, as he continued to build an international career.
In November 1989, he gave a impromptu performance at the Berlin Wall as demonstrators tore it down, a show that was reported around the world.
Later the cellist was rehabilitated by then Soviet leader Mikhail Gorbachev, and he was able to return to Russia to perform.
In August 1991, he flew to Moscow to support Mr Yeltsin as hardliners attempted to reverse Mr Gorbachev's glasnost and perestroika reforms, spending days protesting in the parliament building.
He latterly divided his time between Russia, the US and France.
In an interview with the BBC World Service in 2002, he said that the letter to Pravda was the best thing he had done in his life.
"The best step was not found in music, but in one page of this letter," he said. "Since that moment my conscience was clean and clear."
The cellist Julian Lloyd-Webber told the BBC that at his peak Rostropovich was "magnetic". "He would walk on and get a standing ovation before he'd played a note," he said.
Your recollections of Mstislav Rostropovich
Slava was an amazing human being and will be greatly missed. A world genius in both music and human rights, he showed us that it was/is possible to live a life of great moral courage and beauty. It was my privilege and honour to hear Slava in one of his first recitals in America after his exile in Ann Arbor in 1975, to play under him as a student and then to work with him at the National Symphony Orchestra in Washington DC. Slava we loved you and will miss you terribly.
Jean Hamilton, Hedgesville WV USA
I can still remember the final note he played at a concert of Don Quixote in London with the LSO a few years back. It still makes my hair stand on end even now. One of a handful of musicians it was a privileged to hear
A truly sad day for all cellists, musicians and anybody that had the honour of meeting this great man. The memory of Slava playing as the Berlin Wall fell is only one of thousands that people will treasure. Rest in peace
Nicholas, Warsaw, Poland
It is with great sadness that we read about the demise of the Maestro Mstislav Rostropovic whom we had the great fortune to have met several times, he was a fantastic cellist and a great conductor but most of all he was a wonderful person who will be greatly missed! May he rest in peace. Christina and Hans Henrik Friis
Christina & Hans Henrik Friis, Bonn, Germany
I shall never forget seeing him perform at the Sydney Opera House 20 years ago. He was a most generous musician. Towards the end of his concert he picked up his chair and put his back to the main audience to face the rows of seats looking down onto the stage from the rear as those seats had looked upon his back for almost the entire concert. He played especially for we students in the cheaper seats. The memory of his generous spirit has always stayed with me.
Lee Mowbray, Sydney, Australia