The Conservative Party “isn’t taking antisemitism seriously”, according to the victim of a “hate” campaign.

Dan Ozarow was targeted with “terrifying” and “traumatic” abuse after Conservative politicians launched a personal campaign against him when he stood as a Labour candidate for Hertsmere Council in 2020.

An investigation commissioned by the party’s HQ did not make a ruling on antisemitism, but said the behaviour of five councillors “may well have encouraged others to send antisemitic posts or messages”.

In the messages from members of the public, Ozarow was called a “Jewish c***”, a “Nazi”, and told he should “go to the gas chambers”.

None of the Conservative councillors have been expelled from the party – and have instead been told to go on a training course. Meanwhile, the local Conservative Association has claimed that Ozarow’s allegations are “politically motivated”.

Speaking to openDemocracy, Ozarow said their “risible” punishments send a “terrible message to those of us who are Jewish or from other minorities that the party isn’t taking antisemitism and racism seriously”.

The councillors sit within the constituency of Oliver Dowden – the co-chair of the Conservative Party – who has previously said he will “turn the tide” against antisemitism.

But Ozarow says was left traumatised and needing professional counselling, while he worried for the safety of his family.

Although the councillors were not found to have been antisemitic themselves, the report said their personalised attack on Ozarow may have led others to be abusive.

Conservative member Paul Morris was accused of posting a huge advert on a digital billboard, suggesting that Ozarow was a supporter of Hezbollah. The advert – which featured a picture of the Labour candidate – was branded to look like part of a fictitious local newspaper called The Hertsmere Times.

The independent inquiry said this was a “vindictive” and “personal campaign” against Ozarow – and a “clear example of negative campaigning”.

But in the wake of the inquiry’s findings, a new billboard advert has appeared once again attacking Ozarow. The new display first appeared last weekend, again under the Hertsmere Times banner.

When questioned by openDemocracy, Morris refused to comment on whether the latest advert could reignite the situation. He also said the newspaper wasn’t fictitious because he owns a registered company of the same name – although official records suggest it is a dormant real estate company with just £1 in the bank.

“The fact they haven’t punished them appropriately is worrying, because people are still doing it,” Ozarow said.

He said the new billboard advert was done out of “sheer spite”, adding: “I had to drive past it with my son in the car this morning praying to God that he didn’t see it.”

The “hate” campaign against Ozarow started while his wife was heavily pregnant, and he received threatening messages about the unborn baby.

“It was a terrifying time,” he said. “I wasn’t equipped to deal with it – I had to have counselling afterwards.”

The episode caused his wife so much stress that Ozarow says they were worried they would lose the baby. “It was just earth-shattering at the time,” he told openDemocracy. “And even before they put the billboard back, I still get trauma every time I go through my own town centre.

A petition calling for Dowden, the local Tory MP, to speak out about the case, has now been shared by prominent figures including the Labour MP Clive Lewis, who criticised the “light” punishments handed out.

Ozarow said: “When MPs get harassed or abused, they’ve got armies of people to help them deal with it. But when it happens to a local councillor, there simply aren’t the support networks in place. I had to deal with an incredible amount of it just with my family and on my own – and a few people in the party I happened to be friends with.”

Despite ruling against the councillors, the inquiry appeared to downplay the allegations made by Ozarow, saying that they “may well have been exaggerated”. Asked by openDemocracy, the Conservative Party did not comment on whether it endorsed this claim.

The Hertsmere Conservative Association said it was “deeply concerned” that Labour had released the investigation’s findings before an appeals process had been completed, adding that allegations of negative campaigning were disputed by all the councillors.

“The named individuals, four out of five of whom are proud members of the Jewish Community, are hurt and dismayed over what are clearly politically motivated claims of antisemitism from Labour.”

Paul Morris refused to comment on the “ongoing” investigation, but said the campaign against Ozarow “at the time was factual”.

A spokesperson for Hertsmere Council said it had not been party to the investigation and hadn’t been approached or formally notified about it.