The Basij militia has been blamed for extreme brutality in the violent aftermath of the contested June 12 election in Iran. A Basij commander, who volunteers for one of the Tehran branch of the militia, describes his account of one the bloodiest clashes, on June 20.

Iran's Basij militia is a pro-government volunteer force which comes to the aid of the regime when unrest hits the streets. It was established by Ayatollah Khomeini in 1979 during the Iran-Iraq war. During the last three weeks the Basij has been called upon by the government to quell the post-election protests, in which at least 20 people were reported to have been killed. The opposition says the figure is much higher.

Mehdi (not his real name) is a 39-year-old Basij commander and a former classmate of one of our Observers from Tehran (who prefers not to be mentioned). Mehdi led a mission in the city centre, close to the Tehran military base, on June 20, one of the most violent days of the clashes.

I did shoot at people myself. I am a military man I have to obey my orders. The crowd was attacking us like crazy people; throwing stones and Molotov cocktails. We had to protect ourselves; to show we were serious, and we did warn them, shouting several times, before opening fire. But they continued to attack. I don't remember who I shot, I just tried to shoot at the people's feet.

Later, we moved back and went behind the vans in middle of the street and I ordered my unit to shoot into the ground in the hope of scaring the crowds from coming closer.

I hoped it would never come to shooting them. That night, I had a nightmare in which the protestors threw me on a fire. It's come back several times, and I can see the faces of the people I was ordered to shoot.  I've asked a very spiritual mullah to pray for me.

I did it for Islam but it wasn't easy to kill people. We have to remember who they are though - they're deceitful people who are against the Islamic Revolution. You can't expect us to stay calm when they want to overthrow our regime."