Dubai: A BBC Arabic documentary about Salafists in Tunisia will be broadcast on Monday.

The Battle for Bizerte which will be broadcast at 19:05GMT tells the inside story of a group of extremist Islamists known as Salafists in Bizerte, a Tunisian town on the Mediterranean sea, 60 kilometres from Tunis.

Through extraordinary and unique access to the group, it reveals how their influence is growing, and why they are perceived as a threat by their opponents and the authorities.

The ousted President Ben Ali’s repressive regime did not tolerate any form of dissent. Thousands of Islamists were locked up for their beliefs. Among them were Salafists. They were released shortly after the Revolution by Tunisia’s new democratic government, ruled by a coalition of parties dominated by the Al Nahda Party.

Now the Salafists are a rising force in Bizerte and throughout the Arab World. Free at last to express themselves and to be politically active post-revolution, they are open about their fervent belief in a literal interpretation of the Quran and Sharia Law.

They want to establish what they see as God’s Law as laid out in the Quran and Hadith (Prophet Mohammad’s Sayings). And they want it to rule in Tunisia and beyond. Their opponents, including the police and the authorities, see them as a threat to democracy and freedom in Tunisia and beyond.

BBC Arabic’s film reporter Zuhair Latif investigates the rising power of Salafism in his country. BBC Arabic has got unique access to Abdul Salam Sharif, one of the leaders of the Ansar Al Sunna, the most powerful group of Salafists in Bizerte.

The group is about 500-strong, which may no seem like many for a city with a population of 260,000. But their power and influence are disproportionate to their numbers. The Ansar Al Sunna are just one of many active Salafist groups in Tunisia. Abdul Salam Sharif owns a small kiosk in the city. This is where he holds court every day from 9am to 6.30 pm with breaks for prayers.

In beautifully-shot observational sequences, we see him welcoming people who come to him with their problems. He helps them with marital issues, legal issues, and much more. He seems to have infinite patience, and gives advice on a variety of problems. He shows compassion and understanding, and true concern about people’s problems.

A woman comes to him for help because her husband wants a divorce and she won’t grant it because she says he wants to sell her house. A former policeman claims that his tenant wants to take possession of his flat. He also deals with more serious problems: a man accused of grooming under-age boys is sent to his kiosk.

The Salafists in Bizerte make their own rules. They believe that they are making the city better as they patrol it for what they consider immoral behaviour, and as they punish people whose actions they condemn.

BBC Arabic filmed them as they challenge, round up and punish people vigilante-style, and as they issue warnings to those who infringe on their strict interpretation of Islamic Law.

In an extraordinary scene with the Salafists on patrol, we see them tell an unmarried young woman they found alone in a shop with a man: “That is not allowed in our religion. You can’t be with him in a private space.”

The film also shows how far the Salafists are prepared to go to impose their views on others. And it reveals how they recruit and how they win hearts and minds through a combination of help, support, threats, and fervent preaching.

The reporter Zuhair Latif challenges Sharif after he and his team witnessed and filmed a group of his followers beating a man they accuse of drinking alcohol.

With a smile, Sharif says the punishment is a measure of the crime. He also accuses the police and the authorities of not doing their job properly. That’s why, he says, people come to him instead of going to the authorities.

The Salafis in Bizerte are filling a vacuum left by a weak local and national government which seems to find it hard to assert its authority after the revolution. Unique and unprecedented access to the police shows them on a stop-and search operation as they attempt to curb rising Salafist power.