A group of Iranian MPs has launched an attempt to sack the country's defence minister over the crash of a military plane in Tehran on Tuesday.
People on the ground were killed as well as all those on board the plane
Forty-nine MPs have signed a motion to impeach Mostafa Mohammad Najjar, saying his mismanagement was to blame for the crash, in which more than 100 died.
Parliamentary authorities will decide whether to allow a vote on the motion.
Observers say the move could be a political embarrassment for President Mahmoud Ahmadinejad.
It comes soon after he resolved a dispute with parliament over his nominations for oil minister.
The text of the impeachment motion was not published, but the authorities have been under pressure over suggestions that the pilot was forced to fly the plane despite raising concerns about its airworthiness.
Lawmaker Gholamhossein Mozaffari told an open session of the parliament: "On behalf of the families of the victims, I expect that dismissal or resignation of the defence minister is the first serious step in dealing with the crash."
The C-130 transport plane, bought from the US before the 1979 Islamic revolution, crashed into the foot of a high-rise housing block after suffering engine failure.
IRAN'S AIR DISASTERS
Feb 04: Iranian plane crashes near Sharjah airport in UAE, killing 43 people
Feb 03: Military transport aircraft crashes in southern Iran, killing 302 people
Dec 02: Commuter plane carrying aerospace experts crashes in Iran, killing 46 people
Feb 02: Tu-154 operated by Iran Air crashes in mountains in west of Iran, killing 117 people
March 97: 80 die when a military plane crashes in north-east Iran
Feb 93: Tu-154 crashes into a military plane near Tehran, killing 132
Most of those killed were journalists travelling to report on military exercises in the south of the country.
President Ahmadinejad has promised to get to the bottom of the disaster.
"The government will hold a serious investigation," he said, before adding: "What is important is that they (the crash victims) have shown the way to martyrdom which we must follow."
The country's civil and military aircraft have a poor safety record.
In 2003, an Iranian Ilyushin-76 troop carrier crashed in south-east Iran killing all 276 Revolutionary Guard soldiers and crew aboard.
Officials blame the high frequency of crashes on a lack of aviation spare parts because of US sanctions.