Russian protest leader Alexei Navalny on Tuesday blamed a criminal probe into demonstrations against Vladimir Putin for a hack attack that saw his e-mail and Twitter accounts filled with obscene messages.
In the early hours of Tuesday, his Twitter profile was changed to "swindler and thief" -- his own term for the ruling party United Russia -- and his regular readers were bombarded by a stream of homophobic insults.
Navalny said he suspected his e-mail and his popular Twitter account, which has more than 250,000 followers, were hacked into using his iPads and computers that investigators confiscated as part of a probe into violence at a protest.
The charismatic lawyer, street orator and anti-corruption investigator is one of the most popular figures heading the divided opposition movement, and has largely built up his profile online.
"My e-mail has been hacked and through it my Twitter. It's obvious that it was through the computers/iPads confiscated in the search," Navalny said, after police raided his office and apartment earlier this month.
"That is what our Investigative Committee is like," he added, writing on Facebook and LiveJournal accounts in the early hours of Tuesday.
The Investigative Committee angrily rejected Navalny's allegations.
It issued a statement on Tuesday morning saying that his claims "do not reflect reality" and accusing him of "pressure and attempts to discredit the investigation" that it warned could merit legal action.
The Investigative Committee, which is in charge of serious crime, is conducting a major probe into violent fights between opposition activists and police on May 6.
So far they have arrested and charged 13 people, and Navalny is being questioned as a witness along with other prominent opposition leaders including radical left-winger Sergei Udaltsov and television presenter Ksenia Sobchak.
Sobchak complained after photographs taken during a raid of her apartment appeared on a tabloid website before they did on the Moscow city police website.
The websites of opposition media are regularly subject to distributed denial of service (DDOS) attacks during protests when they stream street footage online.