Speaking at a forum in Argentina Tuesday, Peres said both Hugo Chavez and Mahmoud Ahmadinejad have gone crazy over oil, which he says is not bad to sell but "really dangerous if you swallow it."

He said both leaders are headed for a fall.

"They won't hold, not because any of us is going to kill them; their own people are getting tired of them," Peres said. "So if you want good relations with them, consider that they are passing passengers. It's a short-term relationship. So don't waste too much on them."

Peres is touring Latin America to counter growing Iranian influence in the region just ahead of a visit by Ahmadinejad to Brazil and Venezuela. The Iranian leader's call for Israel's annihilation hasn't stopped Chavez and Brazilian President Luiz Inacio Lula da Silva from asserting their own strategic interests in close ties with Iran, which Israel views as a major strategic threat.

Lacing his tough criticism with jokes, Peres seemed sanguine in an appearance organized by Argentina's foreign ministry. The Israeli president even referred to Chavez's recent exhortations to Venezuelans to save energy and water by taking shorter showers.

"I must say that with some of the things he says, I agree with him completely, 100 percent. For example, he says you shouldn't sing in the bathroom. I agree with him. He says it's anti-socialist to be in a Jacuzzi, 100 percent. I have tiny soaps, not too bad," he said, drawing laughter from the audience.

But Peres also noted Chavez's recent drop in the polls.

"I see the latest polls that show most of the people are dissatisfied with him," Peres said. "If I could vote in the poll, I know exactly how I would vote. Because the problem is not just what Venezuela is doing for Chavez but what Chavez is doing for Venezuela. It's not a serious government."

Peres also accused both leaders of wasting their oil reserves in an attempt to buy prestige.

"There's something in common between Ahmadinejad and Chavez, oil makes them think a bit complicated," he said, twirling his right hand near his head as if to suggest both leaders are crazy.

"It's really dangerous if you swallow it. It's not bad to sell it but don't drink it too much. And wheresoever there is oil, there is problems as well. You lose your sense of proportion," he added, speaking in English. "Let's not forget that oil is not being produced. It's not the result of human engineering. It's being discovered. And you don't know where it is going to be discovered or how long it will last."