Prime Minister Vladimir Putin opted on Tuesday not to return to the stage of Moscow's Olimpiisky stadium, where a crowd of 20,000 met him with catcalls last weekend.

Putin was slated to attend an anti-drug gala, studded with pop stars and organized by the controversial charity Federation — incidentally, run by a former Kremlin official.

Billboards with Putin's visage and the slogan, "Bros, you don't need this," dotted Moscow streets in the weeks leading to the event. But Putin never showed up for the free show, which attracted a crowd of 10,000, most of them young people.

Putin's spokesman Dmitry Peskov confirmed by telephone on Tuesday afternoon that his patron would not visit the event, but did not elaborate.

However, most observers, including bloggers, were quick to suspect bad memories. On Sunday, a publicity stunt went wrong for Putin at Olimpiisky, where a mixed martial arts match took place between Russian favorite Fedor Emelianenko and America's Jeff "Snowman" Monson.

Emelianenko won, but when Putin came to the stage to congratulate him, he was met by a wave of jeers and boos. He plowed through with his speech, nevertheless, with his voice trembling a bit.

Peskov and several other officials tried to downplay the event, insisting that the jeers were for Monson. But the fighter's Facebook page on Tuesday was filled with comments from Russian fans saying they liked him and booed Putin.

The Tuesday event did not go down well, either. At some points, the crowd at Olimpiisky started chanting, "Yes to drugs."