Making matters worse for the sanctions-hit country, Britain, France and Germany triggered a dispute resolution mechanism under the already tattered 2015 nuclear deal, prompting Iran to warn them of unspecified “consequences”.
The Ukraine International Airlines plane was brought down by a missile shortly after takeoff on Wednesday, killing all 176 passengers and crew on board.
Iran has struggled to contain the fallout over its handling of the air disaster, after initially dismissing Western claims it was brought down by a missile before admitting it on Saturday.
The tragedy has seen hundreds of angry protesters, most of the students, take to the streets, apparently chanting slogans against the Islamic republic.
AFP correspondents said around 200 mainly masked students gathered at Tehran University on Tuesday and were locked in a tense standoff with youths from the Basij militia loyal to the establishment.
“Death to Britain,” women clad in black chadours chanted as Basij members burned a cardboard cutout of the British ambassador to Tehran, Rob Macaire, after his brief arrest for allegedly attending a demonstration Saturday.
Kept apart by security forces, the groups eventually parted ways.
The protests have been much smaller than nationwide demonstrations against fuel price hikes that turned deadly in November.
But one commentator said the latest rallies showed there was a “real rift between the people and the authorities”.
“I hope that (police restraint) will continue and that no lives are lost because this could be a catalyst for more protests,” Mehdi Rahmanian, director of reformist daily Shargh, told AFP.
In another sign of growing dissent, a group of artists cancelled their participation in the Fajr festival, held each year on the anniversary of the 1979 Islamic Revolution, according to Hamshahri newspaper, which is owned by Tehran City Hall.
Tehran had for days denied Western claims based on US intelligence that the Boeing 737 had been downed by a missile.
It came clean on Saturday when Revolutionary Guards aerospace commander Brigadier General Amirali Hajizadeh acknowledged a missile operator had mistaken the plane for a cruise missile and opened fire independently.
Judiciary spokesman Gholamhossein Esmaili said the first arrests had been made over the air disaster, without naming them or specifying how many.
“Extensive investigations have been carried out and some people have been arrested,” he said.
Esmaili also said around 30 people had been arrested in the protests over the air disaster.
The announcement came shortly after President Hassan Rouhani said about the air disaster that “anyone who should be punished must be punished”.
“The judiciary must form a special court with a high-ranking judge and dozens of experts… The whole world will be watching,” he said.
“It cannot be that only the person who pressed the button is at fault. There are others.”
The Kiev-bound plane was shot down at a time when Iran’s armed forces were on heightened alert after launching a volley of missiles at Iraqi bases hosting US troops.
Iran fired the missiles in retaliation for a US drone strike on January 3 that killed Qasem Soleimani, the head of the Guards’ Quds Force foreign operations arm.
Addressing that issue, Rouhani said while “the root of all sorrows goes back to America… this cannot be a reason for us not to look into all the root causes” of the air disaster.
Canadians join probe
The president also demanded officials explain why it took so long for authorities to announce the real cause of the air disaster.
But Rouhani said that for him it would be more important that Iranians are “assured that this incident will not be repeated”.
Iran has invited experts from Canada, France, Ukraine and the United States to take part in the probe.
On Monday night, Canada’s Transportation Safety Board (TSB) said its investigators flying to Tehran would be granted access to the wreckage and black box flight recorders.
“There have been early signs that Iran is allowing the TSB to play a more active role than is normally permitted,” its chair Kathy Fox said.
On the diplomatic front, Britain on Monday summoned Iran’s ambassador to lodge its “strong objections” after its Tehran envoy, Macaire, was temporarily arrested for allegedly attending a demonstration on Sunday night.
Iran’s judiciary spokesman on Tuesday described Macaire as a “persona non grata” and said his “obligations under international treaties are clear”.Source: