Anti-Kremlin punk band Pussy Riot performs in Prague

A woman reads a leaflet during a protest rally in support of the detained members of the Russian all-girl punk rock band Pussy Riot in Prague June 19, 2012.

PRAGUE (Reuters) - Anti-Kremlin, punk-rock band Pussy Riot gave a typically impromptu performance in Prague on Tuesday in support of three of its members detained since March for singing a protest song against Vladimir Putin in Moscow's main cathedral.

Two members of the all-woman collective popped up on a balcony just off Prague's central Wenceslas Square and danced to the soundtrack of previous performances.

Wearing the band's trademark brightly colored balaclavas in line with a pledge of anonymity, the women unrolled a large three-part red banner demanding "Free Pussy Riot" above a bustling, pedestrianised street.

Pussy Riot was part of a protest movement against Putin's 12-year rule that at its peak saw 100,000 people take part in a wave of street protests in Moscow. It was also seen as a challenge to the Church over its involvement in politics.

One of the women, who declined to reveal her name, said the performance was a tribute to fellow band members awaiting a decision by a Russian court on Wednesday on whether to extend their custody without bail for another two months.

"Tomorrow is an important day because the court will decide on further detention," she said at a cafe in Prague, where she said she and her fellow band member have fled fearing arrest.

"We will go back to Russia but we will be very careful not to get caught," she said.

Defense lawyers for the jailed women said they had filed an appeal against their detention to the European Court of Human Rights on Tuesday.

They face up to seven years in jail for a performance in Moscow's Christ the Savior Cathedral on February 21 in which they derided the Church's close relationship with the state and appealed to the Virgin Mary to "Throw Putin out!".

That show, in short dresses and bright masks, offended Russian Orthodox church goers, but the detention of the women, two of whom have young children, has also raised an outcry from human rights groups who say their arrest is unjustified.

Amnesty International has called for the release of the three members in Moscow, but a court hearing in April extended their custody.

(Editing by Louise Ireland)