The image of a Muslim man pleading with his imam for a second chance with his wife, only to be told that it is his wife's decision, is not what most people would expect from a sharia court. But his case is typical of hundreds each year dealt with by a group of scholars who provide judgments on sharia law for Muslims across the country.

Sharia law has not only become synonymous with brutal punishments meted out by hardline Islamic states; it has also come to be seen as a source of oppression within Muslim communities across Europe. The Qur'an has been used to justify forced marriages, honour killings and even the call to holy war by fundamentalist clerics such as Abu Hamza. But sharia also has another face. Islamic law is a code for living that governs every aspect of life, from which food is halal, to donations to the poor and the proper way to dress. The Muslims who consult the Islamic Sharia Council are not asking for permission to stone adulterous wives, or chop off the hands of thieves, but simply for day-to-day guidance on living in accordance with their faith.

"The only thing we want sharia to mean here is when it comes to their religious belief, their marriages, their divorces, their right to prayer," says Mushtaq Bux, until recently general manager at the Leyton council. "That is what we mean by sharia, nothing else."

The council, which has no legal authority, issues fatwas, or religious judgments, from two rooms that resemble a hard-up solicitors' practice, tucked away on a quiet terraced street of small family homes with roses in the front gardens. It considers everything from inheritance settlements and whether property deals comply with Islamic laws against accruing interest, to the proper time to start Ramadan (in a country that is always overcast, how can you rely on the first sighting of the crescent moon?) and whether a soft drink that advertises itself as a non-alcoholic alcopop can actually be allowed to call itself alcohol-free. In one email, a woman who is losing her hair asked if Muslim women are allowed to wear wigs.

But the overwhelming majority of cases are to do with divorce - 95% of the roughly 7,000 cases the council has dealt with since opening its doors in 1982 - and, specifically, with releasing women from bad or forced Islamic marriages. When he worked at the Leyton council, Bux used to get about 40 letters and emails a day from women asking for divorces. "People don't understand the scale of the epidemic," he says.

The flood of applications stems from husbands' misuse of Islamic laws on marriage. Under Islamic law, a man is allowed to have up to four wives and has the primary right to call for divorce, known as talaq. As a result, it is possible for a husband to leave his wife and re-marry, refuse to give his first wife a divorce, and still consider himself living in accordance with his faith. In the eyes of the Muslim community, his first wife is still married, and because women are only allowed one husband at a time, she is stranded. "She is left hanging in midair," says Najma Ebrahim, a coordinator with the Muslim Women's Helpline, which receives 2,000 calls a year, 70%-80% of which are from women with marital problems. And with divorce comes stigma from the community. "To them, the woman is a failure: she couldn't keep her husband."

The council writes to the husband on behalf of the wife - a process known as khul'a - and asks him to grant his wife talaq. If he does not agree, or refuses to respond, after three months the council aims to issue a divorce.

Ebrahim says the council is providing a vital service. "It's very important for [the wife's] self, for her healing," she says. "Her faith - her fate - is important to her, so when she goes to the council and gets that decision, at least for her she knows she is not doing something wrong." Suhaib Hasan, the secretary of the council, puts it more bluntly. "If she remarries without taking the divorce, she would be an outcast in society," he says. "This is why she has to have an authority where she can get the solution of her problems."

When Razia, 40, left her home in Manchester for rural Pakistan two years ago, she thought she was just going to visit her family. But when she got there she found herself under intense pressure to marry a man 10 years her junior. After weeks of emotional blackmail by her aunt and her aunt's family, eventually she gave in. She explains how she was ground down by her family and disorientated by being thousands of miles from home. "I did tell them I'm not over here to get married, but they weren't taking no for an answer," she says. "When you are over there with your family, family wins."

She quickly realised the marriage was really about obtaining a visa for her new husband. "They just wanted to get it over and done with, thinking he'd get the visa straight away," she says. "I have had no contact from him since he found out it was not a quick process."

As soon as she got back, she set about trying to get a divorce, but as a Muslim, she not only needed a civil divorce but an Islamic one as well. She felt the Islamic Sharia Council were the only people who could help.

The council says her case is typical, and Sayeed, 55, president of the council, is furious that sharia law is used to justify forced marriages like Razia's. He says that forced marriage is an ingrained cultural tradition, but it is not sanctioned under sharia law. It is a "tribal or traditional interpretation of Islam", he says. "Not incorrect interpretation of sharia - no interpretation of sharia."

"In every situation our motto is: reconciliation first. So we try to reconcile, but in cases where a marriage was enforced on a girl against her wishes, against her own opinion, we don't want to negotiate. What we do is, we try to make their guardians, their parents, understand the Islamic position, and also we tell them what is the position of British law on marriage." Sayeed tells them that they "will also be guilty of [breaking] heavenly laws - that is how we try to convince the parents". Does it work? "Not all the time. We are human and working in human society. Not all the time; most of the time, yes."

But not all councils are as committed to liberal interpretations of sharia. Estimates of the number of mosques across the country range from 1,000 to 2,000. They serve a hugely diverse Muslim community - at 1.6 million people, Muslims are the largest religious minority in Britain. Each mosque has its own imams, some of whom are scholars like Sayeed, while others are simply devout Muslims fulfilling a need for religious guidance in their communities. The Islamic Sharia Council is one of the oldest and most respected, but it admits that there is no single body that can claim to be fully representative of all British Muslims.

Neither is there any regulation of imams, or any benchmark for the quality of advice that they give. Abdul Jalil Sajid, former secretary of the mosque and community affairs committee of the Muslim Council of Britain, estimates that 35% of imams are unqualified. No one knows how many of them are operating in sharia councils, applying their own interpretations of Islamic law.

According to Cassandra Balchin, of Women Living Under Muslim Laws (WLUML), too many of them promote a highly conservative interpretation of sharia that overemphasises the rights of the husband. "They don't seem to recognise the multiple forms of divorce that are available to women," she says. "There are usually no women involved, whereas in a lot of Muslim countries you can have women judges involved in family courts."

"They are bringing the husband in and saying, can he please release her." But, says Balchin, "If the husband has violated his wife's rights within the marriage, Islam gives the wife the right to divorce irrespective of his consent. The woman is left with this feeling that she is powerless and that she has to beg for everything. This is a very conservative interpretation."

The question of which councils are at fault is as hard to pin down as the range of interpretations of sharia. Shahien Taj, founding director of the All Wales Saheli Association, says that this confusion itself leaves many women bewildered and uncertain of their rights. "If I can't get my head around it, I can't expect anyone else to," she says.

Parvin Ali, founding director of the Fatima Women's Network, which is based in Leicester, counsels women on the receiving end of one-sided judgments. She says she has not seen women from the Islamic Sharia Council in Leyton, but has heard complaints about councils elsewhere.

Another major problem is bad advice over what exactly constitutes a valid marriage and divorce in the first place. The councils "seem to imply that their decisions would be valid in some other legal context", says Balchin, "but that, in fact, is not the case".

Islamic marriages and divorces conducted in Muslim countries such as Pakistan or Bangladesh are recognised as valid in the UK, but the British courts do not recognise Islamic ceremonies carried out in this country unless they are registered separately with the civil authorities. The result is that some Muslims think they are protected by family law when they are not, and others think they are properly divorced when, in fact, they are still married. In one case, Luton police contacted WLUML after pursuing a man for bigamy who had married in Luton, then flown to Pakistan and married again. After looking into the case, they found that the first marriage was invalid as it had been conducted by an imam in an unregistered mosque. His first wife was left with no legal protection by the family courts, and the husband was free to bring his second wife back to Britain as his legal spouse.

There are also consequences for ex-husbands. One 39-year-old man came to the Islamic Sharia Council after he had split up with his wife, whom he had married Islamically but not civilly. They have a young daughter, and he had provided the down payment on their home, which is in his ex-wife's name. All the sharia council could do was issue a recommendation that under sharia law their assets should be split proportionally, and that both parents should have equal access to their daughter. But as they were not legally married, the husband had no claim over the family home, and when his wife began to prevent him from seeing his daughter, he found he had very limited rights as a father.

"I don't have a leg to stand on," he says. "If I approach her house holding a letter from the sharia council ... if she calls the police, it's not a letter that can be used in a court of law."

The Islamic Sharia Council, along with other sharia councils, argues that much of this confusion could be swept away if sharia law on marriages and divorces were recognised under civil law. But according to Lord Justice Thorpe, deputy chair of the Family Justice Council, there is already legislation available to them. "It seems to me they haven't really got a problem at the marriage end," he says. "All you have to do is register your place of worship and, once registered, then marriages solemnised will be good in civil law."

And as far as divorces are concerned, he sees no reason why a recent act brought in to tackle the problem of so-called limping marriages in the British Jewish community, could not also be applied to British Muslims. But that is as far as it is likely to go. "What we can't accept is marrying polygamously under English law," Lord Thorpe says.

According to Werner Menski, professor of South Asian Laws at the School of Oriental And African Studies and an expert on comparative law, the rather vague demands of the sharia councils are as much about British Muslims attempting to define what they mean by sharia, as they are about incorporating Islamic law into the British legal system.

"At the moment, there is a period of confusion and insecurity," he says. "The question is, how far can we go in this pluralism, how far can we go in accepting these things? But don't expect any answers - it's really very difficult. Everybody in this field is scratching their heads about how to do this."

In the council's backroom, however, surrounded by gold-embossed tomes of Islamic jurisprudence and brown cardboard boxes, Sayeed puts his hand on his chest with pride as he explains what his work means to him. "I feel I could at last do some real good thing in the practical life of people," he says. "I am not doing it for any financial gain in this world; I am doing it for immense reward from the Lord Almighty in the hereafter, so it fills my heart with all these riches".