Twelve-year-old walks off with 117 carat diamond necklace - with video

Hong Kong police were on the hunt Monday for a teenage girl who they say made off with a multimillion-dollar diamond necklace over the weekend.

No arrests have been made so far, police confirmed, after the robbery on Saturday at a jewellery shop reported to be in southern Kowloon.

Around 3 pm, three well-dressed adults distracted staff while a girl estimated at between 12 and 14 years old stole a key, opened a locked cabinet and slipped the necklace worth 36 million Hong Kong dollars ($4.6-million) into her pocket, the South China Morning Post reported.

The trio, two women and one man aged between 30 and 40, stayed on in the store while CCTV footage showed the girl calmly leaving the mall compound.

"The necklace was embedded with more than 30 diamonds totalling about 100 carats," a police source told the newspaper.

After spending more than 30 minutes in the shop - reported to be the Emperor Jewellery shop in southern Kowloon - the four left without buying anything, the South China Morning Post reported.

Detectives described the heist as "very well planned."