KIEV: A Ukrainian anti-corruption activist and journalist who reported on organised crime died Thursday after being attacked, police said.

Vadym Komarov was attacked in May in the city of Cherkasy where he worked, around 200 kilometres (124 miles) from Kiev. He suffered serious head injuries and fell into a coma.

He died in hospital early Thursday, Ukraine's police chief Sergiy Knyazev said.

Investigators are working to establish if he was attacked because of his work, interior ministry spokesman Artem Shevchenko told AFP.

They are also considering whether the attackers could have had a personal conflict with the journalist or acted for financial gain.

Police have questioned more than 1,300 people in the case but have failed to identify the attackers, Knyazev said.

Komarov reported on corruption and organised crime in Cherkasy and had been attacked before, local media said.

Reporters Without Borders said it was "shocked" by Komarov's death.

"We demand from the police a rapid investigation to find those who are guilty," Oksana Romaniuk, the head of Ukraine's Institute of Mass Information, an NGO, wrote on Facebook.

Journalists have relative freedom of speech in Ukraine, which has a wide range of media, but security remains a concern. Attacks on reporters are not uncommon and the perpetrators are often not found.

In November 2018, Ukrainian anti-corruption campaigner Kateryna Gandzyuk died after being injured in an acid attack several months earlier.

Journalist Pavel Sheremet was killed by a car bomb in 2016 while driving near his home in Kiev.

In 2000, the founder of the respected news site Ukrainska Pravda, Georgiy Gongadze, was kidnapped and found beheaded in a forest outside Kiev. Ukraine has jailed the killers but the masterminds have never been brought to justice.

Ukraine, a former Soviet republic, ranks 102nd out of 180 countries in a world ranking of media freedom by Reporters Without Borders. —AFP