A Pakistani father-of-six is on the run after strangling five of his children to death, apparently believing the sacrifice would endow him with magical powers including alchemy, police said Friday.

Ali Nawaz Leghari, 40, killed the two girls and three boys, aged between three and 13 overnight Thursday in the village of Saeed Khan, some 230 kilometres (140 miles) north of the city of Karachi.

"The man's financial condition was bad but he was also learning black magic and it seems that he made the sacrifice to excel in the craft," police officer Qamaruddin Rahimo told AFP.

Amjad Sheikh, the district's police chief, confirmed the incident which occurred while Leghari was undertaking a 40-day spiritual journey, known as a 'Chilla' prescribed to him by a pir (living saint) that he hoped would teach him the art of alchemy.

Rahimo said that on Tuesday Leghari had attempted to poison the family's dinner but was spotted by his wife, resulting in a bitter quarrel.

The wife along with their eldest son left the house to go and stay with her parents.

With the pair out of the way, Leghari was able to successfully carry out his plan to sedate the remaining five children and then used a rope that was found at the scene to strangle them, said Rahimo.

"He strangled them one by one inside the room and later dumped them on a bed in the courtyard," he said, adding police were now hunting Leghari down.

Black magic practices are rooted in mystic Sufi lore and have traditionally been the domain of pirs and aamils (sorcerers).

The practice is particularly strong in rural parts of the country including the impoverished southern Sindh province where the killings took place.