Thousands of Iranians, including children, watched in fascination and horror as two men convicted of murdering a hardline judge were hanged in Tehran yesterday, the first public executions in the capital for five years.

Majid Kavousifar, 28, and his nephew, Hossein Kavousifar, 24, were jostled in handcuffs to two pickup trucks where nooses dangling from cranes 5m (16ft) high were tied around their necks.

Before them was a huge portrait of Hassan Moghaddas, the judge whom they shot dead in his car in front of his central Tehran office two years ago. When the hoods of his killers were removed, the older man smiled and puffed out his chest. He waved at the crowd and chatted to his executioner, whose face was masked. The nephew was silent, trembling and in tears.

The hangmen kicked away the wooden stools on which the two stood, the ropes snapped tight, and a shout of “God is greatest” erupted from the crowd. The older man appeared to die instantly. His nephew writhed for a few seconds before his body went slack.

Some onlookers laughed. Others, perched on the roofs of buildings, captured the scene on mobile phone cameras.

The tearful mother of one of the killers cried: “God, please give me back my son.” From a balcony through loudspeakers, an official boomed: “Death to hypocrites! Death to the terrorists! Death to America!”

The murdered judge had worked in a “guidance court” that handles sensitive cases of “moral corruption”. He had jailed seven dissidents in 2000 after they attended a conference in Berlin on Iranian reform.

Officials claimed that his killers were not political activists, saying that the older convict had admitted to a personal vendetta against the judge whom he considered “corrupt”. Tehran’s hardline chief prosecutor, Saeed Mortazavi, said: “People like him [the killer] should know their actions will not dissuade our judges from carrying out their deeds.” The killers were also convicted of armed robbery and other murders, Mr Mortazavi said.

Only China executes more people than Iran. Yesterday’s hangings in Tehran brought to at least 151 the number executed in the Islamic Republic so far this year, compared with a total of 177 last year, itself twice the number executed in 2005.

Officially the draconian punishments are deterrents aimed at “elevating security” by cracking down on “thugs and hooligans”. But the campaign coincides with the toughest crackdown in years against political and social dissent that has targeted students, academics and journalists as well as women and labour activists.

There has also been a sweeping campaign against young people flouting the dress code, with women upbraided for wearing figure-hugging clothes and men chided for sporting Western-style haircuts.

The regime, showing signs of paranoia, claims that dissenters are trying to topple the Islamic system in a “soft revolution” backed by the US.

Times Recommends

• Rio Tinto four held as China prepares case
• Diplomats must keep heads down and trousers up
• When in Rome should one make like Berlusconi?