The family of the murdered Maltese investigative journalist Daphne Caruana Galizia have had little chance to mourn her death because of continuing intimidation, threats and lies, according to her son.

Paul Caruana Galizia, told the Hay literary festival in Wales that it felt like the family was at war with the state seven months after his mother was killed by a car bomb near her home.

Caruana Galizia worked for 30 years as an investigative journalist looking into high-level corruption cases.

At the time of her death, there were almost 50 lawsuits against Caruana Galizia, five of them criminal defamation cases. The remainder were civil libel suits. Some of these have been dropped but 34 remain against her estate.

Paul Caruana Galizia told the festival that threats and misinformation had continued after her death, including one rumour that the bomb was planted by his brother.

All three of Caruana Galizia’s sons have left Malta and continue to highlight the case. “It is a war,” Paul said. “It really should not be like this, but we can’t rely on the investigation to be run properly. We just can’t sit back and think that things are moving.”

Another story being circulated in Malta was that Caruana Galizia was investigating criminal gangs, not the government, which was nonsense, he said.

He was joined on stage by the Maltese journalist Caroline Muscat. “What the family has had to face is absolutely horrendous,” she said. “They have not even had the time to mourn the loss.”

Muscat said the government continued to intimidate and threaten journalists who were investigating and publishing things it did not like. “The only truth is that of the government … If anything it has redoubled its efforts.

“Criticism of the government in Malta has become a very dangerous thing. We have a situation where there is an almost complete dominance of public discourse and narrative by the government. Anyone who continues to fight that is discredited, dehumanised … and Daphne is the culmination of all that is wrong with this system.”

Rachael Jolley, the editor of Index on Censorship, said she was shocked by what was going on in Malta, a country in the European Union and the Commonwealth, and where so many British people go on holiday.

“Outsiders have got no idea that this is all happening underneath,” she said.

Muscat encouraged visitors to Malta to go to Caruana Galizia’s memorial at the law courts to light a candle, “speak to people [and] challenge ideas. We have a certain lack of awareness and education on what our rights are.”

The BBC Europe editor, Katya Adler, who chaired the discussion, said the Maltese government denied allegations of threats and intimidation.

Three men have been arrested on suspicion of detonating the bomb that killed Caruana Galizia. They have all pleaded not guilty. The Maltese government has said the investigation into the murder has continued. Questions about the motive for the attack remain to be answered.