Russian activists on Wednesday briefly put up a huge banner on a building opposite the Kremlin urging Vladimir Putin to quit power, as they prepare for a march through the city later this week.
Braving temperatures of minus 20 degrees Celsius (minus four degrees Fahrenheit), activists from the Solidarnost (Solidarity) opposition movement installed a 140-square-metre white and yellow banner on the roof of an office building overlooking the Kremlin.
The banner showed Putin's face crossed out and read "Putin -- leave."
"It was there for 40 minutes, then it was removed," activist Anastasia Rybachenko told AFP.
"Our main goal was to remind everyone that a demonstration in support of honest elections is being planned for later this week."
"We also wanted to say that it was Putin who created a system under which honest elections are not possible."
On Saturday, Russia's protest movement is set to hold its third mass rally in less than two months in a crucial test of whether it can keep up its momentum to pose a sustained challenge to Putin's rule.
Solidarnost, which also includes fierce Kremlin critic Boris Nemtsov and former chess champion Garry Kasparov, said no-one was detained during the stunt.
"We climbed a fire escape ladder, put the banner up high and froze terribly," Solidarnost leader Ilya Yashin wrote in his blog.
The strongman prime minister is seeking to win back his old Kremlin job in March presidential elections in the face of an outburst of protests against his 12-year rule.
Calls from the opposition are multiplying for Putin to quit the presidential race after serving two consecutive presidential terms between 2000 and 2008 and a term as prime minister.
A recently penned song by paratroopers calling Putin a "tyrant" has become a hit on the Russian Internet.