Daphne Caruana Galizia, a Maltese journalist who led the Panama Papers investigation into corruption on the tiny island nation in the Mediterranean, was killed by a car bomb on Monday.

Prime Minister Joseph Muscat, whom Caruana Galizia targeted in her blog “Running Commentary, condemned the killing as a “barbaric” act, Agence France-Presse reported.

“What happened today is unacceptable on various levels. Today is a black day for our democracy and our freedom of speech,” he told reporters.

Caruana Galizia, 53, had just driven away from her home in Mosta, near the capital Valletta, when the bomb obliterated her Peugeot 108 and sent her body flying over a wall and into a field.

No one has come forward to claim responsibility for the attack.

Muscat described Caruana Galizia – who was recently described by Politico as a “one-woman WikiLeaks” — as “one of my harshest critics, on a political and personal level.”

“But nobody can justify this barbaric act in any way. I will not rest until justice is done,” he added.

A local TV station reported that the journalist had filed a police complaint this month about threats she had received.

In the final entry on her blog, posted about an hour before she was killed, Caruana Galizia reiterated an allegation that Muscat’s chief of staff, Keith Schembri, was a “crook” who used his government influence to enrich himself.

“There are crooks everywhere you look now. The situation is desperate,” wrote Caruana Galizia, who leaves behind a husband and three sons.

She had alleged that Muscat’s wife, Michelle, as well as Muscat’s energy minister, held offshore holdings in Panama.

Michelle Muscat was accused of being the beneficial owner of a secret Panama bank account, which Caruana Galizia had alleged was used to stash kickbacks from Azerbaijan’s ruling family.

Muscat, who won power in 2013, and his wife deny they held such companies and sued Caruana Galizia for defamation.

He called the claims the “biggest lie in Maltese political history” and asked a magistrate to investigate. He has vowed to step down if any link is established between him and hidden offshore accounts.

Caruana Galizia’s death comes four months after Muscat’s Labour Party won a resounding victory in a general election he called early as a result of the scandal.

Malta has a population of 400,000 and is the European Union’s smallest state.

Maltese President Marie-Louise Coleiro Preca called for calm.

“In these moments, when the country is shocked by such a vicious attack, I call on everyone to measure their words, to not pass judgment and to show solidarity,” she said, The Guardian reported.

With Post wires