Checkpoints have sprung up all around Tehran since the start of the war, with residents reporting teenagers in plainclothes manning some of them with machine guns.

Iranian authorities have launched a recruitment drive dubbed "For Iran" in Tehran to register people to join the security forces, lowering the minimum age of recruits to 12.

Rahim Nadali, an official with the Guards in Tehran, told state television that people as young as 12 could register to help the Guards and the Basij youth volunteer militia stand "against the global bully", a term used for the United States.

The tasks include "collecting security data and operational patrols" as well as organising caravans of cars at night in the city, he said.

"At the Basij checkpoints and patrols that you see across the cities, we had a very high number of volunteers among young people and teenagers who wanted to participate," he said.

"Considering the ages of those requesting to join, we have now lowered the minimum age to 12 years old, because children aged 12-13 want to be involved."

Tehran residents have told AFP journalists outside the country of seeing armed youths around the city since the war broke out with the United States and Israel.

"Military pickup trucks with heavy weapons mounted on them block the roads and search cars. You pass them, and just 100 meters ahead, there are several private cars with teenagers holding Uzis (sub-machine guns), again stopping vehicles," said resident Kaveh.

"When a missile hits somewhere, the area is immediately sealed off. Untrained teenagers with Kalashnikovs shout orders at people -- 'stand here, stand there'" and regularly fire warning shots into the air, he said.

Another Tehran resident said at night supporters of the Islamic republic "take cars fitted with speakerphones and they give them flags and they march with lots of noise and shout slogans in the streets".