The European Commission called Tuesday for the "full truth" on the murder of Maltese journalist Daphne Caruana Galizia one year ago, as well as the killing of Jan Kuciak in Slovakia this year, stressing the need to protect free speech and the media.

Caruana Galizia, a vocal critic of Malta's centre-left government, was killed on October 16, 2017, by a bomb placed under the seat of her car.

She was investigating the impact of the Panama Papers tax avoidance scandal in Malta, implicating the prime minister's chief of staff as well as a senior minister.

Kuciak and his girlfriend were shot dead in February at the journalist's home, near Bratislava. At the time he was working on a story about links between the Slovak government and the Italian Mafia.

"We don't want these murders to have a chilling effect on free media," commission Vice President Frans Timmermans, EU Justice Commissioner Vera Jourova and Digital Economy Commissioner Mariya Gabriel wrote in a joint statement.

"That is why the persons responsible for these assassinations must be brought to justice. We want the full truth," they added.

"We need to send a clear signal to all journalists: it is safe to work in Europe. If journalists are silenced, so is democracy," the commissioners wrote.