Isna/Mehdi Ghasemi, via Reuters

Last January, as Iran’s leadership struggled to contain postelection protests, nerves frayed to such an extent that the country’s president, Mahmoud Ahmadinejad, was slapped in the face by a military commander at one contentious meeting, according to a confidential Iranian source who spoke to an American diplomat in a neighboring country.

The incident, which reportedly took place during a meeting of Iran’s Supreme National Security Council just two weeks after several protesters were killed at a protest in Tehran, was described in a leaked U.S. diplomatic cable sent to Washington from the American embassy in Azerbaijan in February 2010.

As the German magazine Der Spiegel first reported last month, the source, whose name was redacted by the news organization (and by WikiLeaks, which published the cable last week), was described as a former Iranian revolutionary activist who “has reported accurately on several sensitive political and economic issues in the past.”

The source told an American diplomat in Azerbaijan that Mr. Ahmadinejad had been slapped by Mohammad Ali Jafari, the commander in chief of the Islamic Revolutionary Guards Corps, for suggesting that perhaps restrictions on the press should be relaxed.

As my colleague Michael Slackman reported in 2009, the powerful Revolutionary Guard force “emerged as a driving force behind efforts to crush a still-defiant opposition movement,” in the weeks after Iran’s disputed presidential election.

Here is the full description of the incident from the cable:

2. (S) According to source, President Ahmedinejad surprised other SNSC members by taking a surprisingly liberal posture during a mid January post-Ashura meeting of the SNSC called to discuss next steps on dealing with opposition protests. Source said that Ahmedinejad claimed that “people feel suffocated,” and mused that to defuse the situation it may be necessary to allow more personal and social freedoms, including more freedom of the press. 3. (S) According to source, Ahmedinejad’s statements infuriated Revolutionary Guard Chief of Staff Mohammed Ali Jafari, who exclaimed “You are wrong! (In fact) it is YOU who created this mess! And now you say give more freedom to the press?!” Source said that Jafarli then slapped Ahmedinejad in the face, causing an uproar and an immediate call for a break in the meeting, which was never resumed. Source said that SNSC did not meet again for another two weeks, after Ayatollah Janati succesfully acted as a “peacemaker” between Jafarli and Ahmedinejad. Source added that the break in the SNSC meeting, but not the slap that caused it, has made its way on to some Iranian blogs.

As the Israeli news site Ynet reported, a spokesman for the Revolutionary Guards denied that the incident had occurred in an interview with Iran’s Fars news agency, which is close to the Guards.

According to the Fars report, the Guard spokesman, Ramezan Sharif, claimed on Saturday that the publication of the cable was part of a plot by the BBC to undermine support for Iran’s government, prompted by demonstrations in favor of the regime. The news agency failed to point out that the cable had been published by Der Spiegel, not the BBC. Mr. Sharif also said that “those behind WikiLeaks,” which Iran’s regime has described as an instrument of Western intelligence, “have availed themselves of the fame they gained through their insider information and invent false stories.”