Madonna has leapt to the defence of anti-Putin punk band Pussy Riot, saying to jail the Russian activists "would be a tragedy".

Maria Alyokhina, 24, Nadezhda Tolokonnikova, 22, and Yekaterina Samutsevich, 29, are on trial for storming the altar of Moscow's Christ The Saviour Cathedral and belting out an expletive-laden "punk prayer" calling on the Virgin Mary to rid Russia of President Vladimir Putin.

However Madonna believes their protest should be seen as a work of art.

The Material Girl said: "I think art should be political. I think art through history, historically speaking, art always reflects what's going on socially. So for me it's hard to separate the idea of being an artist and being political."

If found guilty, the trio face up to seven years in jail - a punishment the Queen of Pop says is wildly disproportionate to their crime.

"I'm against censorship, and my whole career I've always promoted freedom of expression, freedom of speech. So obviously, I think what's happening to them is unfair. And I hope that they do not have to serve seven years in jail, that would be a tragedy."

Accused of hooliganism motivated by religious hatred, the three woman on trial said they wanted their performance to be considered as a political act directed against the church merging with state security services.

Madonna was in Moscow to play a concert as part of her world tour.