Tehran, Iran - Flags belonging to Bahrain and the Lebanese group, Hezbollah, flutter gently as the crowd take their places.

The men, from all hues of Iranian society, wash themselves. It's a ritual common to all Muslims, a physical purification, in readiness for a spiritual message.

Except this is not a mosque or traditional house of Muslim worship. This is a vast auditorium, belonging to Tehran University.

On Friday it is transformed into a giant prayer hall. At one end a stage adorned in blue and silver houses the speakers - spiritual leaders and clerics - who are expected to bring the message to the people.

The official sermon is given by Ayotallah Siddiqui. He speaks softly and offers advice and words of spiritual guidance.

But before him another man speaks. He is neither a cleric, nor a spiritual leader. He reads an officially sanctioned message.

It is one of solidarity - solidarity with Bahrain protesters.

He is a bespectacled man wearing a grey-blue suit.

Saudi-Bahrain deal

The Iranian government has objected to a deal struck between Saudi Arabia and Bahrain for greater co-operation.

They fear what will happen in Bahrain.

Quietly at first, and then with each passing sentence, his voice gets louder.

His words are imbued with a mixture of passion and fury.

He urges the faithful to show compassion with the Bahraini [protesters] who he says are followers of Imam Hossein, the most important Imam of Shia Islam.

Iran is overwhelmingly Shia. That the government here supports the Bahrain protesters in their struggle for freedom is not a surprise.

And the speech reflects that.

Towards the end of the first speech, the shout goes up "Marg Bar Amrika" or "Down with America".

The Iranians see the US as backing the Saudis in their deal with Bahrain. But the Saudis are not spared either.

Impassioned performance

The Saudis are predominantly Sunni Muslims. Bahrain’s royal family is Sunni Muslim.

This makes Iran uncomfortable. The speaker articulates that feeling.

By now some of the faithful are on their feet, one fist clenched, punching the air and shouting.

It is an impassioned performance designed to show the strength of feeling Iran has towards the Bahrain protest movement.

By the time the crowd comes out onto the street, there is a riot of red-and-white Bahraini flags and men and women are chanting.

The state broadcaster is in full effect, satellite trucks and multiple cameras and reporters are on hand to capture every angle.

Iran has got its message across. At least to its own people.

Whether anyone in Saudi Arabia or Bahrain pays any attention, is another matter entirely.