Russian President Vladimir Putin says he does not favor harsh punishment for members of a punk rock band on trial in Moscow for alleged hooliganism.

Mr. Putin's comments Thursday to Russian reporters are his first public pronouncements on the February arrest and prosecution of three members of the all-girl band Pussy Riot.

The defendants, who have spent the past five months in jail, were arrested after performing a political “protest prayer” at Moscow's main cathedral, just weeks ahead of elections that returned Mr. Putin to the presidency. Their trial, which has drawn international attention, opened Monday. The defendants facing possible seven-year prison terms if found guilty.

Earlier Thursday, leading British musicians, including Pete Townsend of The Who, called on Russia to free the defendants.

In an open letter published in The Times of London, the musicians described the charges as “preposterous” and called the cathedral performance “legitimate political protest.”

The letter was published as Mr. Putin arrived in London for talks with British Prime Minister David Cameron.

Afterwards, Mr. Cameron said he raised the issue of the band with the Russian leader as part of wider discussions of human rights.

Mr. Putin, who is facing growing criticism for trying to silence dissent, has in the past issued carefully phrased comments about high-profile court cases that appear just ahead of final verdicts.

In 2010, he famously said “a thief belongs in prison” as a Moscow court deliberated the fate of oil tycoon Mikhail Khodorkovsky. Days later, the court found the defendant guilty of embezzlement and money laundering and issued a six-year sentence. The oilman and a co-defendant were already serving eight-year terms for fraud.