* Anonymous group attacks www.kremlin.ru website
* Internet users report blockage lasting several minutes
* Website targeted after Putin's return to Kremlin
By Vladimir Soldatkin
MOSCOW, May 9 (Reuters) - Hackers temporarily blocked President Vladimir Putin's web site on Wednesday, carrying out a promise to disrupt government information portals two days after his swearing-in for another six-year term that has drawn street protests.
The hacker activist group Anonymous used the "Op_Russia" twitter account to publicise the attack, saying "kremlin.ru - TANGO DOWN" and "Anonymous shuts down Kremlin's websites".
Internet users in Russia said they were unable to access the www.kremlin.ru website for several minutes on Wednesday.
"All the relevant departments are taking the necessary measures to counteract (such) attacks," a spokesman for the Kremlin Internet security division said.
"This is routine work. There is always some external influence. Today we are witnessing a splash of activity (by the attackers) ... (But) they failed to achieve their goal."
Putin won a presidential election in March and on Monday launched his third term as head of state, a day after some 50,000 protesters took to the streets of Moscow over what they called a rigged vote.
Police forcibly dispersed the rally, although it had been approved by the Moscow city authorities, and several opposition leaders were detained.
Last week, Anonymous said it would attack Russian government websites in support of opposition protests.
Anonymous hacked into the emails of a pro-Kremlin youth organisation earlier this year in what it said was a response to a growing number of hacker assaults by pro-government groups on independent news outlets and opposition bloggers.
For their part, pro-Kremlin activists are increasingly using underground hacker networks to suppress the political opposition and independent media which they see as a threat to Putin's hold on power, the Britain-based human rights advocacy website OpenDemocracy said in a report last month.
But the increasing accessibility to hacker tools in Russia has also given the political opposition a chance to inflict damage on pro-Kremlin targets.
(Editing by Mark Heinrich)