* No one hurt in explosion at newspaper offices
* Vijesti says blast is murder attempt on editor
* Newspaper fiercely critical of government (Updates with Djukanovic, EU)
BELGRADE, Dec 27 (Reuters) - A bomb blast shook the offices of Montenegro's leading daily Vijesti in the latest attack on a newspaper known for its criticism of the authorities under long-term leader Milo Djukanovic.
No one was hurt in the blast, which appeared to target a room used by editor-in-chief Mihailo Jovovic, shattering windows and damaging the facade of the building in the capital, Podgorica, shortly before midnight.
Jovovic said he was in his office and another 15 people were in the building at the time. "Glass shattered all over the office, one window was blown in and smoke filled the room," Jovovic told reporters.
Vijesti director Zeljko Ivanovic said the attack was a murder attempt on the newspaper's editor.
"This was the expected outcome of years of campaigning by the prime minister (Djukanovic), his government, his party and the mafia against independent media and primarily Vijesti," he said in a statement.
It was not clear what kind of explosive device was used. Vijesti said security cameras had captured a man in a black jacket planting a package in front of the building and leaving the site about a minute before the blast.
The Interior Ministry said it was looking for a man and a black Opel Corsa car in connection with the incident.
The attack follows a bomb blast in August outside the home of Vijesti journalist Tufik Softic. The newspaper's offices were pelted with stones in October during tensions over Montenegro's first gay pride march. Cars belonging to the paper were torched in 2011.
Vijesti is a fierce critic of Djukanovic - Montenegro's dominant figure since the collapse of Yugoslavia in the early 1990s - and the cosy political and business elite in the tiny Adriatic republic of some 660,000 people.
It frequently reports on accusations of high-level corruption and organised crime, major concerns for the European Union as it tries to steer Montenegro through the reforms required to join the bloc.
Djukanovic, in response to the attack, was quoted by local media as saying: "The police and prosecutor will have to show they are competent to deal with this problem, or they will be replaced."
The Organisation for Security and Cooperation in Europe, however, said past failures to punish such incidents had sent "a message of impunity".
"Only a swift prosecution of all those responsible for these criminal acts can help to ensure that similar attacks not will be repeated," OSCE media freedom representative Dunja Mijatovic said in a statement.
EU Enlargement Commissioner Stefan Fuele tweeted: "Attack on media=attack on democracy. Must be investigated swiftly."
(Reporting and writing by Aleksandar Vasovic; Editing by Matt Robinson and Alison Williams)