Police are tracing the whereabouts of two Hong Kong teenage girls, believed to have gone missing in Argentina. Rainbow Chan, 17, last spoke to her family two days ago. She had previously told her boyfriend she was being held by men who were demanding money for a valuable vase she had broken. Chan flew from Hong Kong to the South American country on February 6. Yuen Long district councillor Kwong Chun-yu said she had rarely travelled before. On February 15, Chan sent a WhatsApp message to her boyfriend, saying she had been held because she had broken an antique vase. Her passport had been confiscated and she faced a US$100,000 compensation bill. "However, at some critical moments [in the WhatsApp chat], like [when asked] how to pay the money, there was no response from Chan," said Kwong. Chan was believed to be in a town near the capital, Buenos Aires, but she had been out of contact for the past two days. Initial investigations by local authorities revealed that Chan was travelling with a 17-year-old Hong Kong girl, only identified so far as Au, and a male friend, also thought to be from the city. Police believe Chan and Au helped someone deliver the vase to Argentina, but on its receipt the pair realised it was broken. The families of the two girls separately made a report to police on Wednesday and Thursday. Police are trying to contact the family of the man. "Hong Kong police have sought help from the Argentine police to verify and investigate the case," a police officer said. "Police are very concerned. We will spare no efforts to locate the three people, making sure their safety is paramount," New Territories North regional commander So Kam-sing said. An Immigration Department spokesman said they had sought help from the Chinese embassy in Argentina and would provide assistance to the families.