Russia's Prime Minister Vladimir Putin failed to make an expected appearance at an anti-drugs concert held in the same venue where he was loudly booed this week, media said today.

Putin was awaited at an anti-drugs concert Tuesday evening in Moscow's biggest stadium and his attendance was advertised on official posters.

The Olympiysky stadium is the same venue where Putin faced what appeared to be an unprecedented outburst of booing when he took the microphone and praised the Russian winner of a no-holds-barred fight on Sunday night.

"The premier decided not to appear in public," said the Vedomosti daily.

Putin's press service, which held a conference call after the booing incident to convince journalists that spectators in fact booed the defeated American fighter Jeff Monson, again sought to quell the controversy.

"Quite unexpectedly, everyone expected Putin to be there," Putin's spokesman Dmitry Peskov said on Echo of Moscow radio. "It is an independent campaign, which he supports, but this event was not on his agenda."

But the prime-minister participated in the anti-drug campaign's previous concert on November 2nd in the Russian exclave of Kaliningrad.

Posters with concerned-looking Putin and a caption reading "Guys! You don't need this!" advertised the Tuesday concert in Moscow's largest stadium.

"Vladimir Putin and stars of stage, sport, and film against drugs," read another caption on the poster hung on streets in Moscow and St. Petersburg.

But the stadium was half-empty during the concert, and no officials could be observed in the audience, the Interfax news agency reported.

Meanwhile Russian fans of no-holds-barred fighting encouraged Monson on his Facebook page.

"Respect for Jeff. BOO for Putin," posted Vadim Boychenko, one of hundreds of people to tell Monson that the stadium protest was not against him.