VIENNA -- OSCE Media Freedom Representative Dunja Mijatović has called on authorities in Albania, Bosnia and Serbia to investigate all hacker attacks on media websites.

The attacks "represent a clear danger to media freedom," a statement said on Tuesday.

“We have seen malicious denial of service attacks recently that obstruct the lawful activity of journalists. They must be investigated by law enforcement agencies of all countries,” Mijatović said.

The OSCE statement noted that in the past two days Internet servers of the FENA news agency and BUKA magazine in Bosnia-Herzegovina were hacked, while last week the website of the Albanian Public Broadcaster was hacked and replaced with provocative images. Media outlets in Serbia: 24sata.rs, Blic, e-novine, Kurir and Telegraf, were also subject to attacks.

“Such attacks are a threat to cyber security, which is vital for free media and the free flow of information,” Mijatović said. “We have witnessed an exponential increase in such attacks which must be thoroughly investigated to protect online portals and allow journalists do their jobs without hindrance.”