A fugitive mainland gang that grooms children to carry out jewel heists across Asia is being sought over an audacious HK$36 million theft in Tsim Sha Tsui early this year. According to police sources in Hong Kong, mainland police have zoomed in on a five-member gang they believe snatched the most expensive diamond necklace in a high-end jewellery store in January from under the noses of staff. The heist was remarkable for a young girl's ability to take a key from a drawer and lift the necklace as a couple posing as her parents distracted the salespeople. Now, police believe the girl is part of a five-strong gang along with two men and two women who have been identified by mainland authorities and have become the subject of a major manhunt. "Intelligence indicates the two men and two women are not the girl's parents," a source told the South China Morning Post . They are thought to be members of a syndicate that has trained and deployed children in a series of robberies across the region, according to the source. "The syndicate strikes not only in Hong Kong, but also in other countries," he said. Police have declined to say if the syndicate is responsible for two identical heists in Singapore and Malaysia last year, but this is also understood to be a major line of investigation. In the Singapore heist on Christmas Day, a girl whom authorities said looked "about 10 years old" stole a high-value diamond ornament from a shop at the Marina Bay Sands complex. She was accompanied by a couple who similarly diverted the attention of shop staff. The Kuala Lumpur case, meanwhile, involved a girl of between eight and 10 who made off with a 5.2 million ringgit (HK$12.1 million) ring from a jeweller's at a Bukit Bintang shopping centre in January last year. She had entered the shop with three women and was believed to have taken the key to the glass showcase, stolen the ring and then put the key back. "The tactics they use are simple, but they work," another source said. "Some distract the attention of shop staff and others do the stealing." Children were assigned to carry out the actual thievery, he said, because they would not draw attention. "After a series of such cases, shop attendants have become more alert," he said. The girl in the Tsim Sha Tsui heist looked to be 12 to 14 years old. She went inside the Emperor Jewellery shop in the 1881 Heritage mall on January 23 accompanied by one man and two women. The three adults kept shop staff busy on one side of the store while the girl calmly picked up a master key behind the counter and took the necklace from a display cabinet on the other side. A man met the girl after she exited the shop with the necklace - embedded with more than 40 diamonds totalling 117 carats - in her jacket pocket. Sources said the five left for Shenzhen in two groups through the Lo Wu and Lok Ma Chau checkpoints hours later. Kowloon West regional crime unit is investigating. No one has been arrested yet, nor has the necklace been recovered.