London (PTI): Police have issued bilingual posters that highlight a 5,000 pound reward for information on the killers of a Chinese couple in Newcastle, media reports said here.

The posters, issued in English and Mandarin after three weeks of murder, highlight a reward of 5,000 pounds for information that could help nab the couple's killers, the BBC said.

Zhen Xing Yang and his girlfriend Xi Zhou, both 25, were found dead with serious head injuries at their flat in the city's West End on August 9.

The report said the couple died after a "frenzied" knife attack and that Zhen had also been tortured before being stabbed to death.

Investigation revealed that the couple were involved in a betting scam over the internet and also traded fake documents such as visas and certificates of qualification.

"It is now almost three weeks since the bodies of Xi Zhou and Zhen Xing Yang were discovered. Since then officers have been working tirelessly to catch their killers," the BBC quoted Northumbria Police Deputy Superintendent Steve Wade, leading the investigation, as saying.

"We have been examining forensic evidence, CCTV, mobile phone and banking records, computer and website data. I hope that anybody who has information and has yet to come forward will see the new appeal and contact my officers," he added.

Police are still looking for three people seen near the flat less than an hour after Xi was last seen alive, the report said.