The websites of Ukrainian President Viktor Yanukovich and the former Soviet republic's interior ministry were put out of action on Wednesday as disgruntled Internet users hit back at the government after it shut down a popular file sharing site.

Ukrainian police closed down Ex.ua, a website used by millions of Ukrainians to obtain movies, music and software for free on Tuesday. Authorities accused it of copyright piracy.

The move triggered an uproar among Ukrainians who bombarded government websites with automated requests which overloaded their capacity.

Unidentified people have been attacking the official website of the president of Ukraine since last night, Yanukovich's spokeswoman, Darka Chepak, wrote in her blog.

The website is used to promote the image of the Ukrainian president, carrying official photographs, speeches and news of official events.

The website of the Interior Ministry has gone down under the attack. Calls are being spread over social networks to join the attack on government institutions' websites in the name of supporting 'file sharing websites' that do not observe copyright laws, Chepak said.

Ukrainian police said on Wednesday they had received numerous complaints against Ex.ua from software companies such as U.S.-based Adobe and had been investigating it since last July.

This week police raided what they said was an Ex.ua office where they seized computers that were used to run the website.

Copyright protection is a tough issue for Ukraine which was included in the list of the most notorious spots for violation of intellectual property rights by the Office of the United States Trade Representative last year.

With an average monthly wage of $330, few Ukrainian can afford to purchase movies, music and software legally and many turn to websites such as Ex.ua where content shared by other users is available free of charge.

Even Ukrainian government bodies may still be using some pirate software installed years ago, officials say, although current laws require them to buy only properly licensed products.

The process of legalizing (software) is under way not only at the Interior Ministry but at other state bodies as well, Interior Ministry spokesman Volodymyr Polishchyuk told reporters.

The Ex.ua case followed a crackdown by the United States on a similar but much larger website, Megaupload, earlier this month, which also triggered attacks on official websites such as that of the U.S. Justice Department.

(Reporting by Olzhas Auyezov; Editing by Richard Balmforth)

Ukraine