A Liberal Democrat peer has said Israel will not last for ever, with her remarks prompting calls for the party's leader, Nick Clegg, to take disciplinary action.

Lady Tonge, who was sacked as the Lib Dem children's spokeswoman in the Commons in 2004 when she suggested she could consider becoming a suicide bomber, made her remarks in a meeting at Middlesex University.

"Beware Israel," she said. "Israel is not going to be there for ever in its present form. One day, the United States of America will get sick of giving £70bn a year to Israel to support what I call America's aircraft carrier in the Middle East – that is Israel. One day, the American people are going to say to the Israel lobby in the USA: enough is enough."

She added: "Israel will lose support and then they will reap what they have sown."

The Liberal Democrat leadership criticised Tonge for the remarks but stopped short of calling on her to withdraw her comments. A spokesman said: "Jenny Tonge does not speak for the party on Israel and Palestine. Her presence and comments at this event were extremely ill-advised and ill-judged. The tone of the debate at this event was wholly unacceptable and adds nothing to the peace process. The Liberal Democrats are wholehearted supporters of a peaceful two state solution to the Israel- Palestine issue."

Ian Austin, a former Labour minister, said: "There is a cross-party consensus that a two-state solution is the only way to bring peace to the Middle East. At the very least, Nick Clegg must make Baroness Tonge withdraw these remarks."

Tonge's remarks were made last week and disclosed on the Guido Fawkes website.

The Liberal Democrat Friends of Israel group dismissed Tonge as an "irrelevant, siren and marginal voice" and called on her to resign the party whip.

Gavin Stollar, chairman of the group, said: "LDFI strongly condemns Baroness Tonge's latest outburst not only because it is wrong but because it is contrary to Lib Dem party policy. Jenny Tonge is an irrelevant, siren and marginal voice in the Liberal Democrat party and we call on her to resign the Lib Dem whip.

"If she truly believes the things she says, how can she justify being a member of a party whose policies are diametrically opposed to her views on Israel and the Middle East, a subject on which she talks on almost a daily basis?"

John Woodcock, the chairman of Labour Friends of Israel, said: ""This is the latest in a series of outrageous remarks from Baroness Tonge - words of excuse or apology in response are no longer enough. Nick Clegg needs to take disciplinary action against his offensive peer to reassure people the government remains serious about a two-state solution."