An Israeli news channel reported Sunday night that Prime Minister Benjamin Netanyahu and Defense Minister Ehud Barak asked the Israeli military in 2010 to prepare for an imminent attack on the Iranian nuclear program, but that their efforts were blocked by concerns over whether the military could do so and whether the men had the authority to give such an order.

The report, by the respected investigative journalist Ilana Dayan, came in the form of a promotional preview for an hourlong documentary about Israel’s decision-making process regarding Iran, which is scheduled to be broadcast Monday night. Ms. Dayan said on the channel’s evening newscast on Sunday that Mr. Netanyahu, in a meeting with a small circle of top ministers, turned to Gabi Ashkenazi, the head of the Israeli Defense Forces at the time, and told him to “set the systems for P-plus,” a term meaning that an operation would start soon.

Mr. Ashkenazi and Meir Dagan, who was the head of the Israeli intelligence service, the Mossad, at the time, would later say that this was an attempt at “stealing a war,” Ms. Dayan reported, because in their view such an order required a decision of the full cabinet, not the smaller group in the meeting, who were then known as the forum of seven.

Both Mr. Ashkenazi, who is now retired, and Mr. Dagan, who stepped down after the meeting, have become vocal critics of plans for a unilateral Israeli attack on Iran, and of Mr. Netanyahu and Mr. Barak’s aggressive approach.

Ms. Dayan said in the preview report on Sunday that the issue deepened a divide in Israel’s top echelon.

Mr. Ashkenazi was quoted saying of the P-plus order: “This is not something you do unless you are certain you want to execute at the end. This accordion will make music if you keep playing it.” But Mr. Barak told Ms. Dayan that “it is not true that creating a situation where the I.D.F. and the country’s operational systems are, for a few hours or for a few days, on alert to carry out certain operations means the state of Israel is compelled to act.”

“Eventually, at the moment of truth, the answer that was given was that, in fact, the ability did not exist,” Mr. Barak said in the clip that was shown on Sunday.

Ms. Dayan said in an interview Sunday night that she learned about the 2010 order from more than two people who attended the meeting, but she declined to name them. Mr. Barak essentially confirmed what she had learned in his interviews with Ms. Dayan, saying that such an order can always be reversed, something Mr. Ashkenazi and Mr. Dagan dispute.

The full report is scheduled for broadcast on the eve of the American elections, and could reopen the rift between Washington and Jerusalem over how best to stop Iran from obtaining an atomic bomb. The Obama administration spent much of the year pressing Mr. Netanyahu and Mr. Barak to hold back on military action against Iran in favor of severe sanctions and intense diplomacy, though the issue receded somewhat after Mr. Netanyahu said in a speech to the United Nations on Sept. 27 that the moment of truth would come next spring or summer, not in 2012.

If the account in the documentary is correct, the episode came at a critical time. That summer, a lengthy effort by the United States and Israel to undermine Iran’s capability to enrich uranium using cyberweapons had threatened to unravel. The effort, code-named Olympic Games, had two goals: to slow the Iranians, and to provide Israel with an alternative to military action, which President Obama feared could start another war in the Middle East. It was partly exposed when a cyberworm found its way out of the Natanz enrichment plant, where it had destroyed or forced out of service nearly 1,000 centrifuges, and began to spread across the world.

In Washington and in Israel, officials met in secret to assess what to do, and Mr. Obama, who inherited Olympic Games from the Bush administration and accelerated it, decided to keep the effort going.

Ms. Dayan said that Israeli censors prevented her from saying when in 2010 Mr. Netanyahu and Mr. Barak gave their order. If it came late in the year, it would suggest that they believed the cyberprogram, once exposed, had little chance of further success, and that they were turning back to plans for airstrikes like the one Israel mounted, on a smaller scale, against a Syrian nuclear reactor in 2007.

The full documentary, the season premiere of Ms. Dayan’s weekly program, “Fact,” on Channel 2, tracks a decade of Israeli decision-making on Iran, from former Prime Minister Ariel Sharon’s discussions with President George W. Bush through Mr. Netanyahu and Mr. Barak’s actions in recent years. The program includes a seven-minute interview with Mr. Netanyahu, conducted on Friday, though in it he declines to answer questions about the 2010 episode.

Mark Regev, a spokesman for Mr. Netanyahu, also refused on Sunday night to comment on the report, except to say that it was incomplete. “He does give a full interview, all about Iran,” Mr. Regev said of the prime minister. “He talks about America, he talks about a lot of things. It’s very interesting, what he does say. It would be best to wait until the full report.”