The implications of the political scandal which cost Priti Patel her ministerial career will have a devastating impact on British Jewry, senior figures have predicted.

Communal representatives and pro-Israel activists believe the affair will bolster antisemitic conspiracy theories and damage relationships with British politicians for a generation.

One senior communal figure said: “This will set us back 20 years.”

Ms Patel resigned on Wednesday night. Earlier that day, the JC reported a version of events directly at odds with the official line put forward by Downing Street.  According to the JC’s sources, Theresa May knew about Ms Patel’s meeting with Benjamin Netanyahu well before last week — and Number 10 asked Ms Patel to leave out details of a meeting with an Israeli official from a statement issued on Monday.

But the involvement of Conservative Friends of Israel (CFI) and its honorary president, Lord Polak, in the affair has led to worries that Israel and the Jewish community could be blamed for future ministerial failings, political scandals and government errors.

One Jewish MP said: “This will feed into the conspiracy theories. It needn’t damage UK-Israel relations, but it will make many people more wary.

“I really don’t know whether CFI and Lord Polak will be badly affected by it, but it’s obviously undermining. It’s certainly not good news for the Jewish and pro-Israel communities.

“In reality it’s about a minister not following the ministerial code — it wasn’t against the national interest, but it’s very serious.”

CFI is the largest such group in Westminster with an open line to almost every Tory MP, dozens of other countries’ diplomatic and political groups, and influence in Downing Street for decades.

But one senior communal figure said CFI would now be regarded as “toxic”.

One Jewish Westminster source played down the Israel aspect, saying: “This isn’t about an ‘Israel lobby’, it’s about people not running meetings by the book. But it is a bit of a feeding frenzy for people with an agenda.”

Another warned that CFI would be helped by “a bit of circumspection and humility” and by “being a bit more careful about perception”.

A leading pro-Israel Tory MP said it was clear that the fall-out from the Patel affair would undermine CFI’s “reputation and good work”, although another communal source said they expected the group’s reputation to be “damaged” but with a “recovery” possible in the future.

A greater concern, they added, was the prospect of the Conservative government’s demise and the potential for Jeremy Corbyn to enter Number 10.

The Board of Deputies and Jewish Leadership Council did not comment on this week’s events.

Ms Patel’s resignation on Wednesday evening came after almost a week of claim and counter-claim over who knew what and when about the International Development Secretary’s meetings in Israel during the summer.

When James Landale, the BBC diplomatic correspondent, first reported concerns about Ms Patel’s meetings last Thursday night — the night of the main Balfour centenary dinner — it was said that she had broken away from a family holiday in Israel to conduct the meetings, accompanied by Lord Polak.

The peer told the BBC last week the pair had “met up for one or two things” while being on holiday at the same time. “I just joined her for a couple of days, some drinks, some dinner, that kind of thing,” he said.

Ms Patel initially told the Guardian that Boris Johnson, the Foreign Secretary, and the Foreign Office had known about her visit, but on Monday she was forced to issue a humiliating apology and further explanation.

In a statement issued by the Department for International Development, she clarified her earlier comments about Mr Johnson and said he “did become aware of the visit, but not in advance of it”.

She went on to reveal details of 12 meetings she held in Israel, including with Benjamin Netanyahu; Yuval Rotem, of Israel’s Foreign  Ministry, and Yair Lapid, the Yesh Atid leader.

Ms Patel added: “In hindsight, I can see how my enthusiasm to engage in this way could be mis-read, and how meetings were set up and reported in a way which did not accord with the usual procedures. I am sorry for this and I apologise for it.”

But further revelations on Tuesday about meetings she held in London and the United States with senior Israelis cast doubt on earlier versions of events and brought Downing Street’s role into question.

It also emerged that Ms Patel had suggested Britain should give aid to the Israeli military to help fund a relief effort for Syrian refugees in the Golan Heights and that she had allegedly visited a relief unit there, although that claim was unconfirmed. Britain does not recognise Israel’s presence in the Golan.

Mrs May’s spokesman confirmed that the idea had been raised by Ms Patel but said there was no change in policy and Britain did not provide funding to the IDF.

On Wednesday the JC revealed that Number 10 had instructed Ms Patel not to include a further meeting with Mr Rotem — in New York on September 18 for the UN General Assembly — on the list published on Monday.

Two sources told the newspaper that she had disclosed the meeting earlier in the week but was told by Number 10 not to include it as it would embarrass the Foreign Office. After the JC published the story on its website, a third source confirmed this version of events.

In addition, according to the sources, Mrs May spoke to Ms Patel in advance of the UN General Assembly and they discussed her meeting with Mr Netanyahu and details of the plan for UK aid to be shared with the Israelis. Mrs May agreed that the idea was sensible but needed to be signed off by the Foreign Office.

After widespread coverage of the JC’s story, Downing Street rejected the  version of events as “not true” and insisted that Mrs May only knew of the Netanyahu meeting last Friday.