JERUSALEM (JTA) — Birthright Israel co-founder and billionaire philanthropist Charles Bronfman said that young Jews are free to criticize Israel — but not while enjoying a free trip.

“If people want to call Israel names and say bad things about the country, they certainly have the right to free speech. But they don’t have the right to do it on our nickel,” he told the Israeli daily Haaretz in an interview published Wednesday.

His comments come after at least two groups of American Jews visiting Israel on the 10-day trip walked off the tour to join left-wing groups on visits to Palestinians. The walk-offs reportedly were encouraged by IfNotNow, a left-wing American-Jewish group.

The young Jews who walked off the trip and some others who remain on them are critical of what they say is Birthright’s failure to deal with Israel’s occupation of the West Bank. Some have complained that maps handed out to participants do not draw a proper distinction between Israel and the West Bank.

Bronfman said in his interview with Haaretz that participants on Birthright can extend their trip and join any kind of group they want or travel on their own to Palestinian areas.

“If they want to go to the West Bank or Gaza, they are certainly free to go,” he told Haaretz.

“What is not fair is making a big tzimmes while the trip is on. Frankly, I just don’t think that is fair to their fellow participants.”

Bronfman expressed concern over improperly marked maps, however, saying he hoped it was a one-time mistake.

He noted that the Birthright experience includes four hours devoted to discussing the situation between Israel and the Palestinians, both in Israel and the West Bank and Gaza, as impartially as possible.

“I don’t see the issue not being addressed,” he said.

Bronfman called the walk-offs a sign of Birthright’s success.

“If we weren’t successful,” he said, “we wouldn’t have the problem.”