MOSCOW, Sept 13 (Reuters) - A large black banner with the words "Death to the usurper Putin" was briefly draped over a billboard on an apartment building in Moscow on Tuesday before being removed.

It was not immediately clear who put up the banner, two days before opponents of Russian President Vladimir Putin hope to draw tens of thousands of people at a protest march and rally.

Putin, in power since 2000, easily won a six-year presidential term in a March election despite a series of opposition protests that were the biggest of his 12-year rule.

The banner hung over half of a large car advertisement on the roof of a central Moscow building. It was soon removed, and police milled around the building.

Putin was in the Black Sea resort of Sochi on Thursday.

In February, opposition activists hoisted a huge banner reading "Putin, go away" on a billboard on a roof facing the Kremlin.

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  • President Vladimir Putin pets his dog Conny before one of his meetings with officials in his office in the Novo-Ogaryovo residence outside Moscow on March 3, 2004. (Alexander Zemlanichenko, AFP / Getty Images)

  • Russian President Vladimir Putin plays with a dog in the village of Verkhniye Mondrogi August 18, 2001, during his summer vacations in Karelia. (Getty)

  • Russian President Vladimir Putin smiles as photographers try to make pictures of his dog Koney during his meeting with Jordan's King Abdullah II (not pictured) at Putin's residence in the Russian Black Sea resort of Sochi Aug.18, 2005. (Alexander Zemlianichenko, AFP / Getty Images)

  • Russian President Vladimir Putin hugs a Hungarian 'Puli' dog owned by Hungarian Prime Minister Ferenc Gyurcsany (R) and his wife Klara Dobrev on the balcony of the Prime Minister residence in Budapest, March 1, 2006. (Miklos Der, AFP / Getty Images)

  • Russian President Vladimir Putin pets his dog Kuni as Germany's Federal Chancellor Angela Merkel looks on as they address journalists after their working meeting at the Bocharov Ruchei residence in Sochi Jan. 21, 2007. (Axel Schmidt, AFP / Getty Images)

  • Russian President Vladimir Putin plays with a dog as former US President George Bush look at him at the Bush family house at Walker's Point in Kennebunkport, Maine in July 1, 2007. Putin arrived in the United States for a "lobster summit" with Bush, aimed at defusing tensions which have spiked over irritants such as missile defense. (Mikhail Klimentyev, AFP / Getty Images)

  • Russian President Dmitry Medvedev and Prime Minister Vladimir Putin, accompanied by a dog, play badminton at the presidential residence in Sochi on Aug. 14, 2009. (Dmitry Astakhov, AFP / Getty Images)

  • Russian President Dmitry Medvedev and Prime Minister Vladimir Putin, accompanied by a dog, drive in an electric buggy at the presidential residence in Sochi on August 14, 2009. (Dmitry Astakhov, AFP / Getty Images)

  • Russian Prime Minister Vladimir Putin hugs a Bulgarian shepherd dog, a present from his Bulgarian counterpart Boyko Borisov after their press conference in Sofia on Nov. 13, 2010. (Nikolay Doychinov, AFP / Getty Images)

  • Russian Prime Minister Vladimir Putin plays with his Bulgarian shepherd dog named Buffy during their meeting at Putin's residence outside Moscow, the Novo-Ogaryovo, on Dec. 9, 2010. (Alexey Druzhnin, AFP / Getty Images)

  • Russian Prime Minister Vladimir Putin greets a soldier's dog as he visits a division of the Ministry of Internal Affairs in Balashiha, outside Moscow on July 22, 2011. (Alexey Druzhnin, AFP / Getty Images)