An award-winning journalist for Ukrainian web-based newspaper Ukrayinska Pravda was killed Wednesday morning by a car bomb, in what Ukrainian authorities have suggested is an effort to destabilize the country.

Pavel Sheremet, an investigative journalist who covered Russia-Ukraine relations and was known for publicly criticizing the Kremlin, was driving to work when the bomb exploded in central Kiev. The vehicle belonged to Sheremet's girlfiend Olena Prytula, the co-founder of Ukrayinska Pavda, Reuters reported. Prytula was not in the car at the time and Sheremet was the only reported casualty.

On Wednesday, Ukrainian President Petro Poroshenko said he believed the attack was an effort to destabilize Ukraine.

"It seems to me this was done with one aim in mind — to destabilize the situation in the country, possibly ahead of further events," Poroshenko said in a television interview.

Poroshenko also said he has asked US Federal Bureau of Investigation officials to assist with the investigation into Sheremet's death.

Russian Foreign Ministry spokesperson Maria Zakharova responded to Sheremet's murder by calling Ukraine a "mass grave" for journalists.

Sheremet, who was Belarussian, frequently used his platform as a journalist to criticize the political elite of Belarus, which he fled to avoid political persecution. Sheremet was later given Russian citizenship and became a close friend of Boris Nemtsov, an outspoken critic of Russian President Vladimir Putin's regime. Nemtsov was assassinated in February, 2015, just steps from the Kremlin.

Nemtsov co-chaired the Republican Party of Russia-People's Freedom Party and also served as the first deputy prime minister under Boris Yeltsin, the late former Russian president who took office following the dissolution of the Soviet Union.

Suspects in the investigation of Nemtsov's murder had alleged ties to Chechnyan ruler Ramzan Kadyrov, a Putin-loyalist who has been a strong supporter of Russia's "anti-Maidan" movement, which aims to halt demonstrations from anti-regime activists.

The Maidan protests of 2014 led to the replacement of Ukraine's pro-Russian government with pro-Western leadership.

Since 1993, at least 56 journalists have been killed for politically motivated reasons in Russia, while at least 12 journalists have been killed in Ukraine in the last decade, according to a tally maintained by the Committee to Protect Journalists.

The deaths include the assassination of Anna Politkovskaya, a Russian journalist who was fiercely critical of the Second Chechen War and Putin, in 2006. Georgiy Gongadze, the other co-founder of Ukrayinska Pravda who was critical of former Ukraine president Leonid Kuchma, was found beheaded outside Kiev in 2000.

The Organization for Security and Co-operation in Europe (OSCE), has responded to Sheremet's assassination by calling for the protection of journalists in Ukraine. OSCE awarded Sheremet a journalism prize in 2002 for human rights reporting in Belarus.