Jeremy Corbyn has condemned Ken Livingstone and expressed regret for describing Hamas and Hezbollah as “friends”, as he faced questions at the Home Affairs Select Committee on anti-Semitism. He also argued that he had not meant to draw an equation between Israel and ISIS last week and said he was “disappointed” that some people made the connection.

During the hearing, Labour MP Chuka Umunna also argued that the left-wing group Momentum could be closed as a way of tackling anti-Semitism in the party.

Corbyn was questioned on a series of remarks made by his long-time political ally Livingstone about Hitler and Zionism in April. Livingstone was suspended from Labour for the comments and his membership is now under investigation. While Corbyn would not comment on the future of the ex-London Mayor’s membership, he said: “I think we have to condemn the way in which he made the remarks and the remarks themselves.”

Corbyn also confirmed that Shami Chakrabarti, who was an observer at the hearing, had taken evidence from Livingstone for her inquiry into anti-Semitism and other forms of racism in the Labour Party.

Corbyn defended the Labour decision inquiry as proof the party is taking seriously allegations of anti-Semitism, saying: “We’re the only political party in Britain that has ever done this”. He said he had taken the decision after being “alarmed by reports” of anti-Semitism within Labour.

Asked about comments he made at the launch of the Chakrabarti Report last week, in which some felt he had equated the actions of the state of Israel and ISIS, Corbyn replied that he had never intended to make a comparison of that sort – and claimed that he he had been referring to “Islamic states” such as Saudi Arabia, and not the group known as “Islamic State”.

“At no point did I make that comparison [between Israel and ISIS], and I’m disappointed that connection was made by the Chief Rabbi or anybody else,” Corbyn said. “I do not make an equation in that way.”

Corbyn also expressed regret for having described the organisations of Hamas and Hezbollah as “friends”- believed to be the first time he has done so over the incident.

He said that using the term “friends” was “inclusive language I used, that in hindsight I wish I hadn’t”. Pushed by committee members to say explicitly that he regretted the incident, he said: “I regret using those words, of course.”

He also appeared to give his support to a two-state solution in the Israel-Palestine conflict, pointing out that it is Labour policy, and accepted that the Hamas Charter (which calls for Jews to be killed) is anti-Semitic, after several questions on the subject.

In one of the most tense exchanges of the hour and 45 minute session, Corbyn clashed with Umunna over the role of Momentum in Labour’s issue with anti-Semitism.

Streatham MP Umunna asked: “In order to help with this anti-Semitism issue, do you not think it would be helpful simply for Momentum to be wound up and shut down?”

Corbyn replied that Momentum had been instrumental in engaging lots of people in politics for the first time, and re-engaging many others. “Surely that degree of engagement in political activity is a good thing,” he said.

But Umunna also argued that many Labour MPs had had their motives questioned over raising anti-Semitism as an issue. He said it was “insulting” to suggest they spoke out on the topic “because we are somehow disgruntled, careerist Blairites”. He said that the issues “have absolutely nothing to do with Tony Blair… or my career… and everything to do with my concern about us upholding the values in our party”.

The Labour leader said that “nobody should be criticised for raising concerns about racism at any time or in any forum. Absolutely not.”