An eight-year-old girl kidnapped from south Delhi allegedly by a drug addict was rescued by the Delhi Police from a moving train in Bihar's Buxar district, an officer on Friday said.

According to the police, Rohit Kumar, 21, kidnapped the girl to extort money from her father to buy drugs.

Kumar came to Delhi to work as a labourer two or three days ago, kidnapped the girl, and made several ransom calls to her labourer father.

"On September 23, a man told police that he worked as a labourer in Jonapur in Delhi and reported that his eight-year-old daughter was missing. He told police that he lived with his daughter only as his wife passed away," Deputy Commissioner of Police (south) Ankit Chauhan said.

An FIR was registered at Fatehpur Beri Police Station following the complaint and an investigation was taken up.

"All formalities, like uploading the details of the girl on ZIPNET, using social media messengers, were done swiftly and a search operation was conducted in the parks, abandoned areas and godowns," said the DCP.

During the course of investigation, a team visited the house of the complainant and collected CCTV footage of the surrounding areas, he said. The footage revealed a person taking the girl with him.

The man was later identified as Rohit Kumar, who had been living in the same locality for the last two-three days at the house of an acquaintance, DCP Chauhan said.

"Rohit Kumar called the complainant on his mobile and demanded Rs 20,000 to be transferred to his mobile, saying his daughter was in his custody. Several calls on his mobile phone were made later, which was a breakthrough for the team. We traced the location of the mobile number near Buxar," said the officer.

Police zeroed in on at least three trains heading towards Patna and the mobile was found active in one of the trains.

"We immediately alerted the Government Railway Police (GRP) and Railway Protection Force (RPF) of Buxar and Arrah. They nabbed the accused in a moving train and the missing girl was rescued. The girl was taken into safe custody. A team of the Delhi police was also sent to Patna," the DCP said.

During interrogation, Kumar revealed he was addicted to drugs and had no money to support his addiction so he abducted the girl.

Except for the headline, this story has not been edited by The Telegraph Online staff and has been published from a syndicated feed.