A Christian mother of three has been kidnapped and forced into an Islamic marriage in Pakistan, campaigners say.

Fouzia Sadiq was abducted from the field where she worked as a bonded labourer on July 23. Her family say that she was taken by her Muslim landlord - Muhammed Nazir - who's brother promised at the time that Sadiq would be returned shortly.

However, after returning for their daughter on July 24, they were told that Sadiq had converted to Islam and was now the property of Nazir, whom she had married.

An officer for the British Pakistani Christian Association (BPCA), has met the family and they will now be moved to a safe house. They say police are refusing to register the incident.

"My sister has been missing for five days and police are refusing to register an FIR [First Incident Report], my heart is broken," Sadiq's sister, Iqra, said.

"Our landlord is a cruel man and we have been starving since he stopped the little payment that was due to us. We have no power and have to face such injustice."

According to the BPCA, incidents of abduction, forced marriage and forced conversion are commonplace. A report from the Karachi-based Aurat Foundation released late last year claimed that between 100 and 700 Christian girls, and around 300 Hindu girls, are married forcibly each year and forced to convert to Islam.

Director of the Aurat Foundation, Mahnaz Rehman, told Fides news agency that incidents are largely ignored by police and civil authorities.

Women face significant discrimination, particularly on a religious basis, she added. Those who are forced to marry are often threatened and pressurised by their husband and his family to declare that their conversion was voluntary, even if the case is taken to court. The Movement of Solidarity and Peace in Pakistan (MSP) says that in the custody of their abductors, girls "may be subjected to sexual violence, rape, forced prostitution, human trafficking and sale, or other domestic abuse."

Chairman of the BPCA, Wilson Chowdhry, said the Pakistani legal system is "set up [to] undermine Christians".

"Fouzia Bibi was a mother of three yet she may still be forced to remain in the forced Islamic marriage despite existing legal precedents from Lahore High court which clearly state that a 'married Christian woman cannot be remarried to a Muslim even if converted'," he said.

"When courts make judgements in these cases more often than not, they forgo the age limit allowing forcible marriages of girls under the legal age of 14, discounting family objections and basing decisions on the testimonies of weeping victims."

Chowdhry added: "The authority of a Muslim man's words significantly outweighs that of Christians, so they have little hope of ever retrieving Fouzia from a life of pain, brutality and debauchery."

Injustices are allowed to "continue unchecked by a government insouciant to the concerns of their largest minority," he said.

The US Commission on International Religious Freedom (USCIRF) in May urged the Obama Administration to designate Pakistan a "country of particular concern" and blamed the Pakistani government for failing to provide adequate protection to targeted groups, particularly religious minorities.

"Forced conversion of Christian and Hindu girls and young women into Islam and forced marriage remains a systemic problem," its annual report said. Hundreds of Christians and Hindus are estimated to be victimised each year.