The Conservative former minister Alan Duncan is being investigated by the party after he said pro-Israel “extremists” within the party, including some ministers and peers, should be expelled because they refuse to support international law.

Duncan, who served as a foreign minister and an aid minister before stepping down as an MP in 2019, named Tom Tugendhat, the security minister, and the peer and former cabinet minister Eric Pickles among those who should be kicked out.

Speaking on LBC, Duncan accused Pickles and another Tory peer, Stuart Polak, of “exercising the interests of another country” by lobbying for Israel through the Conservative Friends of Israel (CFI) group, which he formerly headed.

In a later interview with Times Radio, Duncan said other Tory MPs and ministers, including Michael Gove, Oliver Dowden, Suella Braverman, Robert Jenrick and Priti Patel, were also extremists for not condemning illegal Israeli settlements on Palestinian land.

He called for Braverman, the former home secretary, who argued this week that Israel is not impeding aid getting into Gaza, to lose the Tory whip.

A Conservative spokesperson told the Guardian that Duncan would be investigated by his party over the remarks to LBC.

In his LBC interview, Duncan said that any support for Israel’s current tactics in Gaza was “morally unacceptable”. “It’s what Israel has been doing for years has been wrong because the Israeli defence does not follow international law,” he said.

“It has been backing and supporting illegal settlers in the West Bank who steal Palestinian land and it is that land theft, that annexation of Palestine, which is the origin of the problem, which has given rise to the Hamas atrocity and the battles we’re seeing.”

Some people in UK politics “refuse to condemn settlements and therefore are not supporters of international law”, Duncan said. “I think the time has come to flush out those extremists in our own parliamentary politics, and around it.”

He said the CFI had been “doing the bidding of Netanyahu, bypassing all proper processes of government to exercise undue influence at the top of government.

“So what you have is a lot of people now sitting around Rishi Sunak who are giving him appalling advice. Let’s start with the head of CFI – or had been for many years – Lord Polak.

“In my view, I think he should be removed from the Lords because he is exercising the interests of another country, not that of the parliament in which he sits, joined by Lord Pickles. They’re the sort of Laurel and Hardy who should be pushed out together.”

Tugendhat, Duncan argued, should be sacked for having previously condemned settlements while supporting the current Israeli conduct in Gaza.

Speaking to Times Radio, Duncan said: “For Suella Braverman today to say that there is not a humanitarian problem in Gaza and there’s plenty of food and she’s seen the photographs. Frankly, it is so disgusting, so repulsive, so repellent that I think she should immediately have the whip withdrawn.”

The Board of Deputies of British Jews said Duncan’s comments “effectively accuse two Conservative peers, one of whom is Jewish, of dual loyalties” and described this as “disgraceful”.

The Campaign Against Antisemitism said it was “not the first time [Duncan] has made accusations of parliamentarians being controlled by Israel”, and called for him to be expelled from the party.

In a later statement, Duncan said he was still awaiting formal notification of the investigation, or the reasons why.

He said: “If this is indeed their intention, I will probably be the only person ever to be reproached for upholding his party’s policy and for defending the principles of international law and justice in the face of others who would undermine them.

“Should they choose to pursue this, they should not be surprised if it rebounds on them massively and proves dangerously harmful to their own reputation.”