Hundreds of dead newborn girls have been found dumped in garbage piles in Pakistan over the last year amid a cultural preference for boys, it has emerged.

A total of 345 babies have been found dead in refuse heaps in Karachi, Pakistan's most populous city, since the beginning of 2017 with 99 per cent of them found to be girls, according to local reports.

In one horrifying case, a four-day-old was found dead with her throat slit. Another newborn was left on the steps of a mosque only to be stoned to death when a cleric assumed it was an 'illegitimate baby', a charity reported.

Hundreds of dead newborn girls have been found dumped in garbage piles in Pakistan over the last year amid a cultural preference for boys, it has emerged (file picture)

According to The News International, activists from the Chhipa Welfare Foundation said it had come across 93 such cases in Karachi with 70 in 2017 and 23 this year.

Child infanticide is a criminal offence in Pakistan and police say poverty and illiteracy are root causes, the report says.

However, Anwar Kazmi, from Karachi's Edhi Center charity, said the majority of cases of infanticide were the result of births out of wedlock.

He said girls born in this situation were being killed because of social stigma with boys more often protected by families.

He said: 'We have been dealing with such cases for years and there are a few such incidents which shook our souls as much. It left us wondering whether our society is heading back to primitive age.'

Child infanticide is a criminal offence in Pakistan and police say poverty and illiteracy are root causes, the report says

The News also points to an Oxford Institute of Population Ageing study that highlighted 'son preference' in Pakistan and said the country needed to address 'inequitable gender norms that uphold the perception that sons are more valuable than daughters'.

A police official is quoted as saying that they can only properly investigate the causes of such deaths once a complaint has been registered.

Last year, the official said, only one case of infanticide was reported to Karachi Police.