The episode has a shone a light on Pakistan's criminal justice system, where underpaid and ill-trained police can be quick to lay false charges that ensnare the innocent in years of legal troubles.

"We have had to move to a secret place because we are poor and the police are putting huge pressure on us to manipulate the case," said Muhammad Yasin, the boy's grandfather. He rejected police claims that the family had produced "the wrong baby" before the court in order to undermine the police case.

Musa was among five people identified in a police "first information report" (FIR) following disturbances in February in a slum area of Lahore when workers for a gas company came to try to disconnect households that had not paid their bills.

According to the FIR, written by a now-suspended assistant sub-inspector, Musa and his co-accused tried to kill the gas company workers and the policemen accompanying them by throwing stones.

Residents maintain there was only a peaceful protest. "There were only women in the houses at daytime and they resisted this discontinuing of supply," Yasin said. "Later, we blocked the road and raised slogans against police."

Lawyers say it is all too common for police to resort to collective punishment of entire families, often at the instigation of the complainant.

"Most of the time people don't really want justice at the hands of the courts," said Sundas Hoorain, a lawyer who specialises in murder cases. "It is really all about taking revenge, and that means making the other party suffer as much as possible by putting whole families through hell."

The charging of toddlers is relatively rare, although there are examples of young children being ensnared in the country's blasphemy laws, which have been much criticised by human rights groups.

Shahbaz Sharif, the powerful chief minister of Punjab, Pakistan's largest province, has ordered an inquiry into the matter.