Witnesses sent pictures of police near Enghelab Square
Protesters have defied a crackdown by the Iranian government, to stage another demonstration against the re-election of President Ahmadinejad on Saturday.
Witnesses say dozens of people were beaten as riot police and militia used batons and teargas to try to suppress the protest in Tehran.
Police earlier warned protesters not to gather but several thousand made their way to the central rally site.
Some people who say they were there, have been emailing the BBC with what they saw on the streets of Tehran.
I was part of the protest in Valiasr Square. When we got there, there were riot police and plain clothes guards shooting at people, I could see that people had been shot and were on the ground. There were also water cannons. We decided to head towards Azadi Square, and there were guards on motorbikes attacking people with batons.
There were thousands of people out on the streets the police were using tear gas - the whole experience was terrifying. Towhid (Unity) Square looked like a battle ground.
There were lots of female protesters - I saw a guard attack one women and then she went back up to him and grabbed him by the collar and said 'why are you doing this? Are you not an Iranian?' - he was totally disarmed and didn't know what to do but her actions stopped him.
There were no ambulances around - people were helping each other - helping the wounded - taking them to safety away from further attacks.
Siavash, Tehran, Iran
Plain clothes guards were carrying batons, and some riot police were blocking protesters from entering the square. The guards used tear gas to push the crowds back. This battle went on for about an hour with the protesters moving forwards then back. The crowd was dispersed when about 50 or 60 guards on motorcycles drove into the crowd dispersing them completely. There were about a thousand or so people there, mostly young people. I left shortly afterwards.
My friends told me that in front of Sattar Khan Street, forces were telling people on megaphones "go away before the basijis attack you". My friends are saying many of the people in Enghelab Square are holding copies of the Koran and are chanting. People are running away through side streets but these forces who are well armed are waiting for them there too. The street is filled with smoke, and the local underground station (Darvaze Dowlat) is also full of soldiers, and they are chasing after defenceless people. There are helicopters from Enghelab Square to Azadi Square.
Today is a different day. I and my friends may never return home. We want the world to at least picture our being killed on streets to help democracy in Iran and save the world. Pray for us.
Farshid, Tehran, Iran
Today we tried to join the protesters in Azadi and Enghelab Square, but every route we tried was blocked by the police. The plain-clothes forces are all Sepah (revolutionary guards), as most of them have the Sepah badge on their clothes. In Sattar Khan I saw with my own eyes two ordinary 40-year-old women being beaten severely with electric batons, for nothing more than raising their voice in protest.
I am around Enghelab Square now. There are plenty of Basijis armed with batons and steel cables standing at the beginning and end of each of the surrounding streets. Their numbers are high. Plenty of them are gathered in Amir Abad street, and I see lots of people going towards Enghelab Street. Ahmad - Tehran
Thousands of police men have gathered and closed all streets that end in main squares. But people have gathered to go to these areas. Ali, Tehran
We set out around 3pm to go to Enghelab Square, but from four different directions our way was blocked. There were riot police and plain-clothes basijis with batons and vans and water cannons blocking the way. From 4pm the crowds started to gather and grow larger. The crowds went towards Azadi Square with their hands in the air in a sign of victory but they were silent. Police blocked the crowds and then started attacking them first with batons then with guns, the crowds stated running away and there were lots of women screaming, it was very frightening.Anon, Tehran
Anti-riot police are hiding in an elementary school building in Jamalzadeh Street, they came out, beat up people and dragged them into the building, it's getting nastier as it goes on. Protesters are not afraid at all, they get beaten, they disperse and come together in larger group in a minute. People have learnt lots of tricks during last week and came out with much guts today. Helicopters can be seen all over the sky and I can see smoke rising from different parts of the central part. They beat people up brutally not knowing that they get more and more angry and used to such behaviour!
Mania, Tehran, Iran
We will continue to protest and we have several reasons to do so. First because we demand our rights. Second because we are not afraid. Third - we will not be fooled. And fourth - in this way, the true face of this regime will be revealed to the whole world.