President Aliyev attends Mstislav Rostropovich's 80th birthday reception

Speculation has risen that Rostropovich is seriously ill since his unexplained stay in hospital. On Monday, he also skipped a concert in central Moscow he was supposed to lead.

Looking weak and weary, Rostropovich sat in black tie and dinner jacket next to Putin and Azerbaijan's President Ilham Aliyev at a gala dinner thrown in his honor at the Kremlin.

After posing for the cameras, he stood up and delivered a speech in a tired and at times slightly slurred voice.

"Colleagues and friends I'm the happiest man," he said. "My family, friends and colleagues are here with me on this day."

Rostropovich, exiled for over a decade by the communist Soviet government, then thanked Putin for arranging the dinner, wished guests a pleasant evening and sat down looking relieved.

The speech had lasted barely 20 seconds.  

Rostropovich, affectionately known as Slava, was born in Azerbaijan and displayed musical talent at an early age. He studied in Moscow and toured around the world.

It was on tour in Paris in 1978 that Rostropovich and his wife discovered the Kremlin had stripped them of their Soviet citizenship for what the government newspaper Izvestia called unpatriotic activity.

The cellist said in a statement he had been robbed of his citizenship "by a stroke of a dictator's pen" because he supported people persecuted in the Soviet Union.

"Dear Slava," Putin said. "From the very bottom of our heart we wish you a happy birthday. We do not only love, know and remember your anniversary but we will also do everything to be worthy of it."

He then walked round to Rostropovich and slung a red sash over his shoulder -- an order of services to the motherland. Reuters