A 14-year-old Christian boy has been murdered and his dead body hung in a tree in Faisalabad, according to a charity helping Christians persecuted in Pakistan.

Zeeshan Masih was visiting his uncle's cattle farm and went out to buy a soft drink.

He did not return home, and was later found hanging from the branch of a tree near his uncle's pastures.

His death was registered by police as natural, despite medical evidence showing sexual assault. The British Pakistani Christian Association (BPCA) said his assailants were two local but unidentified Muslim men.

One police officer claimed the boy died of a heart attack induced by drinking a soft drink after eating fruit.

After pressure from the BPCA, a local church and a local bishop, the police have now agreed to register an incident after a DNA report is received in about a month.

Kanwal Amar, lead reporter for the BPCA, said: "This family are deeply traumatised. They have lost a son to an extremely heinous crime and the chance for them to get justice is limited. The manner in which police officers have attempted to camouflage this crime has hurt and angered them. They are calling for an independent inquiry into the handling of their son's death."

Wilson Chowdhry, chairman of the BPCA, said: "The brutal nature of the crimes inflicted on Christians in Pakistan is the product of their vulnerability and the warped minds that breed in the nation.

"The levels of rape, sodomy and murder in Pakistan are reaching unprecedented levels. Christians and other minorities are a natural target as they are disenfranchised by the country's laws and statutes, which confer second-class citizenship upon them.

"In the main Christians are poor, illiterate and hold a pariah status culminating in an ineffectual response from statutory authorities when help is needed, who deem them worthless. No amount of laws can ever change a deeply entrenched community mindset that believes Christians are anathema – so crimes like this will continue and justice will fail time after time."

BPCA has offered to pay for the funeral and is raising funds for the family to have a legal advisor to press for a full murder investigation. The BPCA has also set up a petition to stop child abduction and organ trafficking.