Opponents of Russian Prime Minister Vladimir Putin erected a huge banner reading "Putin, go away" on a rooftop facing the Kremlin on Wednesday in a bold display of disapproval of his plan to return to the presidency in an election next month.
Police later removed the banner and were investigating the incident, Moscow police spokesman Arkady Bashirov said.
A picture of Putin, his face crossed out with an X, stared from the black-and-yellow banner across the iced-over Moscow River at the Kremlin, the seat of Russian power now occupied by President Dmitry Medvedev.
Posters and chants urging Putin to give up power are common at demonstrations sparked by claims of fraud in his party's favour in a parliamentary election in December.
But the banner, which bore the logo of the opposition movement Solidarity, was one of just a few such big displays near the Kremlin since he came to power in 2000.
"We think 12 years under Putin's rule is more than enough," said Pavel Yelizarov, a Solidarity activist who stood in the cold on the embankment near the building.
A Solidarity leader, Ilya Yashin, said the banner faced the Kremlin because "Putin was and remains the master of the Kremlin."
"He is the constructor and ideologue of the political system that has destroyed competition in this country," Yashin said in his blog.
Putin angered middle-class urban Russians eager for change when he announced plans in September to return to the presidency, which he held from 2000-2008, in the election.
Polls indicate he will win a six-year term despite a decline in popularity and the biggest opposition protests of his rule, which are set to continue with a march in central Moscow on Saturday.
Putin has promised limited political concessions but has at times ridiculed the protests and accused their leaders of being in the pay of the United States and Europe.
"We realised that the authorities are not listening to our protests, even after many thousands of people gathered," said Yelizarov. "We're looking for new forms (of protest) demanding Putin leave office."
Yashin said activists put up the banner -- which was affixed to a billboard atop a seven-storey building -- after climbing a fire stair and quickly left when they were done.