A 2,000-strong Pakistani mob snatched a mentally unstable man from a police station, beat him to death and torched his body after he allegedly burned pages from a Koran, police said Thursday.

The mob ransacked the police station in a village on the outskirts of central Pakistan's Bahawalpur city, some 100 kilometres (60 miles) south of Multan, on Tuesday after officers refused to hand him over.

Local police station chief Ghulam Mohiuddin said Ghulam Abbas, in his early 40s, was taken into custody after people said they caught him burning pages of the Muslim holy book.

"After some time, more than 2,000 people surrounded the police station and asked the police to hand over the man to them, and upon refusal they ransacked the police station and took the accused with them," Mohiuddin told AFP.

"The protesters also set fire to several motorcycles and vehicles parked in the police station and damaged the quarters of police officials.

"Later they took away Ghulam Abbas to a main crossing, beat him to death and set his body on fire."

He said the man was mentally unstable and "was not aware of even the location of his residence".

District police chief Ahmed Ishaq Jahangir told AFP the mob was too much for the police to handle after some in the group incited others to take action.

The independent Human Rights Commission of Pakistan (HRCP) demanded an inquiry into the killing.

"HRCP... strongly condemns not only the burning to death of a man in Bahawalpur, who had been accused of desecrating pages of the Koran, but also the authorities' failure to prevent a horrendous crime that was not at all unexpected," the group said.

Pakistan is majority Muslim and its anti-blasphemy laws make defaming Islam or the Prophet Mohammed, or desecrating the Koran, punishable by death.

Former Punjab governor Salman Taseer was shot dead in January last year by one of his police bodyguards for opposing the tough laws.

In June another mob attacked a police station north of Quetta demanding a man detained for allegedly burning a Koran, with the incident leaving one protester dead and 19 wounded.

In February, reports that Americans set fire to Korans on an American base in neighbouring Afghanistan sparked riots that killed at least 40 people.