The woman, thought to be in her early twenties, was found by a motorist at Hawford on the A449 near Worcester, West Mercia police said.
Police could not confirm whether the body was that of Celine, a 19-year- old French accountancy student, but are certain it is not Louise Smith, an 18-year-old clerical assistant who vanished after leaving a party in Yate, Somerset, early on Christmas morning.
A West Mercia spokesman said the body was found naked and no clothes had been discovered near by, although he added that it was too early to say how long it had lain in the wooded area near the lay-by, or how the woman had died.
"We are still trying to establish the identity of the dead woman," he said. "We're treating this as a suspicious death, although it's a murder scale inquiry."
A Home Office pathologist was due to conduct a post-mortem examination last night.
More than 100 detectives from three forces have been searching for Celine Figard who disappeared at a motorway service station on the M4 in Berkshire10 days ago.
She had been travelling to spend Christmas with her cousin, who works at an hotel in Fordingbridge, Hampshire.
She was last seen accepting a lift from a lorry driver who, despite public appeals for information, has not been traced.
Earlier this week her father, Bernard, a 44-year-old farmer, travelled from their home in Ferrieres-les-Scey, south-east of Paris, to make an emotional appeal for help in finding his daughter.
Detectives from Avon and Somerset stepped up their hunt for Louise Smith yesterday.
Ms Smith, from Finch Road, Chipping Sodbury, near Bristol, was last seen shortly after leaving the Spirals nightclub at nearby Yate.
Her departure from the club at about 2am was captured on a security video.
She was thought to have refused the offer of a lift from friends in a taxi, but a former boyfriend said he thought he saw her getting into a blue Ford Fiesta car driven by a girlfriend, but no trace has been found of the car or the driver.
Chief Inspector Piet Biesheuvel of Avon and Somerset Police said: "This is now a major investigation to track down a missing person.
"Although there is no suggestion that [Louise] has come to any harm, her disappearance is totally out of character and we are extremely concerned."
Police investigating the two unconnected disappearances said they had had good responses from the public to their appeals for help.