Israeli Prime Minister Benjamin Netanyahu blew up at the U.S. ambassador last month because he was "at wits' end" over what he sees as the Obama administration's lack of clarity on Iran's nuclear program, a U.S. congressman who was at the meeting said.

House Intelligence Committee Chairman Mike Rogers, a Republican, made his first public comments about the late August meeting in Israel in an interview with Michigan's WJR radio on Tuesday.

Continued controversy over the meeting comes as President Barack Obama on Thursday night will accept his party's nomination at the Democratic National Convention, where the level of the Obama administration's support for Israel was a contentious topic.

"Right now the Israelis don't believe that this administration is serious when they say all options are on the table, and more importantly neither do the Iranians. That's why the program is progressing," Rogers said.

Iran says its nuclear program is for peaceful energy purposes.

Israel is facing growing international pressure not to unilaterally attack Iran's nuclear infrastructure and the United States has made clear it opposes any such strike.

Rogers said if the United States does not show Israel more clarity on where it draws "red lines" on Iran's nuclear program, then Israel might conduct a strike.

"If I were betting my house today, I would guess that they probably will do it if we don't have a change in more clear red lines from the United States," he said.

A spokesman for Israel's embassy in Washington declined to comment. The State Department would not comment on private diplomatic meetings but spokesman Edgar Vasquez said, "We have a rock solid relationship and an ironclad commitment to Israel."

The spat between Netanyahu and U.S. Ambassador to Israel Daniel Shapiro appears to confirm a deep chasm over how to deal with Iran, which the two allies have tried to play down publicly.

Obama has vowed to prevent Iran from obtaining a nuclear weapon, but says there is still time for sanctions and diplomacy to work. The White House says it has brokered international oil and banking sanctions that are far tougher on Iran than previous administrations achieved.

The original purpose of the meeting was for Netanyahu and Rogers to discuss intelligence cooperation and other matters. But it "devolved" into a sharp exchange in which Netanyahu confronted Shapiro with a lot of frustration about the lack of clarity on the administration's position on Iran's nuclear program, Rogers said.

"The uncertainty about where the United States' position is on those questions has created lots of problems and anxiety that I think doesn't serve the world well and doesn't serve peace well," Rogers said.

In an interview with an Israeli television station on Sunday, Shapiro dismissed an Israeli newspaper account of the heated closed-door exchange as "a very silly story" that did not reflect what actually happened in the meeting where the conversations were "friendly and professional." Netanyahu has not commented on the exchange, which was first reported by the daily newspaper Yedioth Ahronoth.

Israel has its own undeclared nuclear arsenal that is believed to contain as many as 200 warheads.

Rogers said the Israeli and U.S. timelines differed on how quickly Iran could put a nuclear weapon on a missile, if it decided to move in that direction.

Netanyahu believes "if they decide to do the dash it could be four weeks to eight weeks," while U.S. intelligence analysts believe it would "take a little longer than that," Rogers said. "But the problem is nobody really knows for sure."