Tony Blair has said Labour has undergone a “profound change” since Jeremy Corbyn became leader and he is not sure it will be possible for “moderates” to regain control of the party.

“It is a different type of Labour party. Can it be taken back? I don’t know,” Blair said on Nick Robinson’s Political Thinking podcast for the BBC.

The former Labour prime minister said he could not imagine British voters at the next election would accept having to choose between Corbyn and Boris Johnson, and a “progressive, moderate” party might step in.

“I just don’t believe people will find that, in the country as a whole, an acceptable choice. Something will fill that vacuum.”

Blair said many people felt “the Labour party is lost, that the game’s over” but he hoped they were wrong.

He said Corbyn and his supporters came from a tradition that had been on the fringe of the party, like Communists or “Trotskyist groups”.

He said he did not think the antisemitism row would have taken place “in the Labour party that I joined”.

“I can’t imagine that we have had three to four months debating over something where we have profoundly insulted the Jewish community in our country,” Blair said.

This week, the Tony Blair Institute (TBI), the non-profit organisation he set up, confirmed in its first set of published accounts that it had received donations from Saudi Arabia, as well as from the US state department, the Canadian government, some African governments and the Victor Pinchuk Foundation, a charity set up by a Ukrainian billionaire.

The Financial Times said the Saudi donation came from an organisation called Media Investment Limited (MIL), a subsidiary of Saudi Research & Marketing Group (SRMG), registered in Guernsey and once chaired by Prince Badr bin Abdullah bin Mohammed al Farhan, now the culture minister.

TBI said it was “committed to working for modernisation and reform”, but on Friday MPs including Labour’s Clive Lewis criticised Blair.

Lewis said the story saddened him greatly “given this country’s record on terror, human rights abuses and likely war crimes”. He said there was “very little that’s ‘moderate’ about taking direct financial support from Saudi”.

The outgoing Green leader Caroline Lucas said: “Today Tony Blair lectures us about socially liberal, progressive politics. Yesterday he confirmed he received up to $12m from Saudi Arabia, which beheads people and is responsible for the slaughter of thousands in Yemen.”