LONDON (AFP) - A young Chinese couple brutally murdered in Britain may have been "sitting ducks" for a gang of thieves targeting foreign students, police said Saturday.

The bodies of Xi Zhou and Zhen Xing Yang, both 25, were found with serious head injuries at their flat in Newcastle, north-east England, on August 9.

Detective Superintendent Steve Wade, of Northumbria Police, said officers were investigating the possibility that they could have been the victims of Chinese gangs operating throughout Britain.

They could have been "sitting ducks" for gangs who believed they had been sent to study in Britain by wealthy families, he told The Journal regional newspaper.

"We're quite keen to explore another potential motive -- whether it was linked to some Chinese organised crime groups targeting foreign students or young people in the UK," Wade said.

"The major line is looking at the targeting of young people throughout the UK, possibly for monetary gain or robbery."

Wade said there had been incidents in London and northeast England in which Chinese people with flats for rent had been robbed or burgled of their possessions.

Officers believe Zhen may have been tortured for up to an hour before his death.

Since the deaths, it has emerged that the couple were involved in an Internet betting scam and trading fake documents such as visas and professional qualifications.

Police took the unusual step of issuing a poster in English and Mandarin on Friday as they appealed for more information.