LAHORE: Pakistani police said on Friday they had arrested a Muslim cleric accused of leading a mob trying to kill a Christian couple for allegedly desecrating the Koran.

Police rescued the Christians from the crowd near the eastern city of Lahore on Thursday, a relatively unusual intervention in a country where those accused of blasphemy are sometimes lynched on the spot.

Police officer Sohail Zaffar Chattha said the cleric leading the mob demanded that police arrest the couple and charge them with blasphemy against Islam.

"I told him I would not register a case because no blasphemy has been committed," Chattha said in a telephone interview.

"But I have registered a case against the cleric and 400 others for inciting violence and endangering the lives of the couple."

About 500 people in Sadar Farooqabad town attacked Owais Masih and his wife after a neighbour complained that they were sleeping on a plastic sheet with verses from the Koran written on it.

Police rescued the couple as the mob began to beat them. The couple were later taken into protective custody and moved to an undisclosed location.

"The mob meant business. They wanted to kill them right there," Chattha said. "And all because they are poor, illiterate people who didn't realise that a line from the Koran was written on a sheet they had purchased."

Blasphemy is punishable by death in Muslim-majority Pakistan. The charge is hard to fight because the law does not define clearly what is blasphemous.

Even presenting the evidence in court can sometimes itself be considered a fresh infringement.

Last year, a British man with a history of mental health illness was sentenced to death for blasphemy.

The same year, a court upheld a death sentence for blasphemy for a Christian woman, Asia Bibi, in a case that drew global headlines after the assassination of two prominent Pakistani politicians who took up her cause.

Pakistan's minorities complain that the state fails to protect them from violence.

Christians make up about 4 percent of Pakistan's population and tend to keep a low profile in a country where Sunni Muslim militants frequently bomb targets they see as heretical, including Christians, and Sufi and Shi'ite Muslims.

Last year, a policeman hacked a man to death for allegedly making derogatory remarks about the companions of the Prophet Mohammad.

Days earlier, a mob beat a Christian couple to death and burned their bodies in a brick kiln.