Twitter diplomacy: Russia rebukes U.S. envoy MOSCOW (Reuters) - Russia rebuked the U.S. ambassador via Twitter on Tuesday after he tweeted his concern at the detention of protesters who challenged Vladimir Putin's presidential election victory. The ministry responded by saying the United States had used much less humane methods when dispersing anti-Wall Street protesters. Russian riot police detained more than 500 people on Monday who either attended unsanctioned protests in Moscow and St Petersburg or refused to disperse after a peaceful rally that had been permitted on Pushkin Square in central Moscow. Within hours, President Barack Obama's new ambassador to Russia, Michael McFaul, wrote on Twitter that he was troubled to see protesters detained in Pushkin Square, often used by dissidents as a rallying point in Soviet times. "Troubling to watch arrests of peaceful demonstrators at Pushkin Square," McFaul, Obama's former White House adviser on Russia, tweeted. "Freedom of assembly and freedom of speech are universal values," wrote McFaul, who presented his credentials to President Dmitry Medvedev, on February 22. Russia's Foreign Ministry, which is trying to project a more modern image by embracing social media, replied to McFaul with criticism of U.S. and European handling of protests against Wall Street and global capitalism. "The police on Pushkin (Square) were several times more humane than what we saw in the break up of the Occupy Wall Street protests or the tent camps in Europe," the ministry replied to McFaul's tweet. Russia and the United States say they are committed to the so-called "reset" of ties which Obama forged with Medvedev, but they still differ over issues including the Syrian crisis and U.S. plans for a missile defense shield in Europe. At a briefing on Tuesday, Deputy Foreign Minister Sergei Ryabkov said Russia hoped to build on the improvements in the U.S.-Russian relationship under Obama and Medvedev. Moscow without hesitation confirms its dedication to this work. There will be no review of these intentions," Ryabkov said, warning the relationship would face a "test of its durability" during the U.S. election campaign. Putin accused U.S. Secretary of State Hillary Clinton in December of stirring protests against his 12-year rule by encouraging "mercenary " Kremlin foes. Washington has dismissed the accusations. McFaul, a Stanford University professor who specialized in analyzing the development of democracy in Russia and the former Soviet Union, was criticized by Russian state television when he arrived to take up his new post in January. Following a meeting with opposition leaders shortly after his arrival, a commentator on state television said McFaul was not an expert on Russia but simply a specialist in the promotion of democracy. Additional reporting by Steve Gutterman; Editing by Timothy Heritage and Ben Harding