Mr Putin’s spokesman and campaign official Dmitry Peskov said the website had been hacked in its early hours and some of the anti-Putin messages were “spam”. He denied messages had been blacklisted for political reasons.
“All this fuss with calls for resignation is a kind of computer game that children are playing at. It has nothing to do with constructive dialogue,” he said.
Mr Putin also unveiled his draft programme for the March presidential poll, which acknowledged Russians’ desire for faster change but barely touched on issues such as corruption and political reform.
He has already faced the biggest protest rallies of his 12-year rule when tens of thousands of people, many affluent and educated city dwellers, took to the streets last month to protest against alleged fraud in the 4 December parliamentary election.
Mr Putin remains Russia’s most influential politician but his popularity has been shrinking since he decided last September to return to the Kremlin after four years as prime minister.
“Vladimir Vladimirovich, I suggest you do not turn the situation into a revolution and resign from the post of prime minister and also take your candidacy off the presidential race,” read a message posted by Svetlana Sorokina.
“Leave politics, please. It is obvious that power is like a drug but it would be a decent move,” wrote Andrei Antinenko.
Anti-Putin messages accounted for at least a third of posts before access was blocked.