Israel and the Palestinians should use the example of South Africa’s reconciliation to achieve a lasting peace, according to FW de Klerk.

The former South African president said that he did not believe Israel was an apartheid state, but warned that it ran the risk of becoming one if it squandered the opportunity to reach a peace deal as soon as possible.

Speaking at a private lunch in London on Monday, the politician who worked with Nelson Mandela to build a new South Africa told leading supporters of Haifa University: “I believe that Israel can learn something from our experience.

“The window of opportunity for a two-state solution will become smaller and smaller and then close. I don’t think Israel is an apartheid state, let me say that unequivocally.

“But if a two nation solution fails, and if Israel becomes a state with borders including where all the Palestinians now live, including Gaza, then who will govern? Will there be an open democracy, one person one vote? Will there be a Palestinian majority in the Knesset? A Palestinian president?”

Dr de Klerk said that in a single state, with Israelis as the minority but “clinging to power and keeping Palestinians under their thumb”, a similar situation to apartheid South Africa could emerge.

He said the violence in Gaza this summer had shaken observers around the world to their “very core” and should act as a catalyst to bring the two sides to the negotiating table.

“We must understand that in conflicts there’s a time to restore the balance of power,” Dr de Klerk said.

“The best time to negotiate is when you can take initiatives, when you are not with your back against the wall, when you have international support to the extent that Israel still does.

“My message is that we managed to escape devastation, to escape catastrophe, by negotiating in a bona fide way and by understanding each other’s core interests.”

Dr de Klerk – who was given an honorary doctorate by Haifa University in May – told the university’s president Amos Shapira and two dozen supporters at the Royal Automobile Club in Pall Mall how he had worked to bring democracy to South Africa.

“We went out of our way to understand the core interests of the ANC. To understand on which issues it would be unreasonable to expect them to give way. Mandela and the team around him did the same vis a vis us,” he explained.

Asked whether Israel and the Palestinians had leaders of the calibre of Mr Mandela, Dr de Klerk said the assassination of Yitzhak Rabin had been “a great tragedy” for the peace process.

One of the strengths of the South African process had been the ability to exclude world powers from the negotiations – a situation “not easily achievable” in the Middle East, he said.

“From the beginning there was an agreement that we were going to negotiate without an arbitrator, without outside chairpersons. We were going to do it ourselves. I don’t know whether that is possible in the case of Israel and Palestine. There are so many fingers in the pie. It is much more internationalised than it was in the case of South Africa.”

The “crisis” of extremism in the Muslim world meant it was hard to build a consensus to put pressure on the Palestinians to act wisely, Dr de Klerk told university supporters including Mick Davis, Victor Blank and Sir Maurice and Lady Irene Hatter.