The most powerful authority in Basra is not the British garrison where more than 5,000 British troops have withdrawn behind barbed wire and cement blocks. It is the Iranian consulate where major decisions regarding the city are taken.

And it is not difficult to see who is in control of the city’s thoroughfares and residential quarters. The roundabouts, major squares and even some small streets and neighborhoods are decorated with portraits of Iranian religious and political leaders.

Basra is perhaps Iraq’s most important province from which most of the country’s oil production and exports originate. Within Basra’s provincial borders, the country’s most prolific oil fields are to be found.

When bombs fall on the British garrison in the city or a British armored vehicle is knocked out, many of Basra residents celebrate with gunfire and shouts of joy.

The Brits have left a huge power vacuum in southern Iraq in the aftermath of their miscalculated adventure. Their influence does not exceed the few square miles of their only base in Basra.

And the militias have rushed to fill in the vacuum, spreading their control over key establishments including oil installations and dividing the city into separate zones of influence.

The country’s three most influential Shiite factions have their own heavily armed militias. Though in bitter rivalry, they are almost unanimous in their tactics to inflict a humiliating defeat on Britain by forcing it to withdraw its troops.

Many of Basra intellectuals and members of its once thriving religious minorities – such as Christians and Mandeans – have fled the city. The militias have their own rules and systems of governing which they impose on their subjects and areas.

Hameed Hussain who fled the city recently says the Iraqi police and army are not in control of the city. "Practically, the militias have the city under their sway."

An oil engineer, Ali Hatroush, who also fled the city in the past few weeks, says the British troops no longer have the power or capacity to "to rein in the militias."

"The fundamentalists are the ones who run the city. They have devised their own means and ways of how to control the people and the resources and liquidate those opposing them," he said.

Abdulkareem Saleh, who used to work at Basra port, said he was sad to see how young people were lured to join the political factions advocating militancy.

"The factions rely on religious slogans and high-ranking clergy to deceive the population. It is really disappointing to see how young Iraqis are being coaxed to join their murderous militias," he said.

The rival factions are represented in the government of Prime Minister Nouri al-Maliki. Nonetheless they are the ones undermining official authority.

For example, the Fadhila party which controls the administrations has 15 deputies in the parliament but has refused to disband its militias.

Other groups like the Sadr bloc has 30 deputies and seven ministers in the cabinet but has strongly rejected calls to disarm its powerful military wing, the Mahdi Army.

The other influential group the Supreme Council, a major partner in Maliki’s coalition government, is reported to have one the most heavily armed militias in the country.