LONDON, England (CNN) -- - Police in eastern England are combing through rural areas hoping to find out who is behind the suspected killings of five women -- all believed to be prostitutes -- that may be the work of a lone serial killer.

Prostitutes were on Wednesday warned to stay off the streets of the Suffolk city of Ipswich, fearing the killer or killers could strike again.

"I'm not sure what starker message there can be at the moment: Certainly three of their peer group have been murdered, now potentially another two," Chief Supt. Stewart Gull of Suffolk police said.

"Clearly it's not safe, they need to stay off the streets."

Investigators looking into the murders of three female prostitutes whose bodies were found outside Ipswich in recent weeks found two more bodies on Tuesday.

While the two bodies have not been identified pending autopsies, police said they feared they were Paula Clennell, 24, and Annette Nicholls, 29, two missing prostitutes, Gull said.

"We haven't heard from them, another night as passed, tragic news," Gull said. "I had hoped to find them ... alive and well but sadly that doesn't appear to be the case."

In a chilling twist, it was revealed that Clennell gave a TV interview four days before she disappeared in which she spoke of her fears. However, she said she had to continue working the streets because she needed the money. (Full story)

Police do not expect to identify the two unidentified women on Wednesday, Gull said. The bodies were left at the scene overnight to preserve forensic evidence.

"It may seem quite callous but we've had to leave them in (that) situation overnight," Gull said. "They'll remain there today in order that we can maximize our opportunity of finding the person or persons responsible."

The other three victims have been identified as Gemma Adams, 25; Tania Nicol, 19 and Anneli Alderton, 24, British media reported. All three women were prostitutes, media reports said.

While it is too early for investigators to conclusively link the two "unexplained deaths" with the three murders, Gull noted that there are "striking similarities" between the crime scenes.

"We know that they're all young females, probably all prostitutes ... all found naked in a rural, open environment," he said.

Gull said police on Tuesday received more than 2,000 tips from the public on the three murders. He encouraged anyone with any shred of information to contact police, noting that the "extra help could make the difference."

A British newspaper on Wednesday offered a reward of �250,000 ($491,000) for information leading to the arrest of the murderer.

"We hope this historic reward will help in solving the series of brutal murders which has shocked the nation," said the News of the World, which is published on Sundays