An Algerian suspected of murdering Briton Isabel Peake and another woman on the French railways could have left the country, police have said.

Detectives hunting 20-year-old Sid Ahmed Rezala travelled to the port of Marseille on Thursday following reports that he had been sighted close to his home in the city in the past 48 hours.

He is wanted both for the murder of Birmingham University student Isabel, 20, whose battered body was found by the main railway line near Limoges in October, and French woman Corrine Caillaux on a train near Dijon this week.

Officers conducting a nationwide search for Rezala, who was released from prison in May after serving a sentence for sex offences, have spent the past 24 hours questioning members of his family and acquaintances on his whereabouts.

A spokesman for Dijon police, where a joint inquiry into the Peake and Caillaux killings is based, said: "Inquiries have been carried out in Marseille following a reported sighting of the suspect.

"We are following up a number of lines of inquiry, among them the idea that the man may have fled abroad or disappeared elsewhere in France. Officers will continue their investigations with a view to arresting this man."

'Series of convictions'

French media reports said Rezela's father, who lives with his family in the Belle-de-mai area of Marseille, had made an appeal for his son to come forward to answer police inquiries.

The reports suggested Sid Ahmed, who was born in El Biar, Algeria, has a long history of psychiatric illness and has a series of convictions for offences including rape, robbery and stabbings.

Ms Peake's body was found lying by the side of the main railway line 75 miles north of Limoges on 13 October after either falling or being pushed from the Brive to Paris express in the early hours.

Detectives investigating the killing travelled to Dijon following the discovery early on Tuesday of the body of 36-year-old Ms Caillaux slumped in the toilet of the Calais-Ventimiglia sleeper service.

She died from multiple stab wounds, including cuts to her throat, during a frenzied attack while her six-year-old son slept in a nearby compartment.

Detectives were able to identify Rezala, who has record for petty crime on trains, after his name was taken by an SNCF inspector for travelling on the Calais-Ventimiglia train without a ticket.

He is thought to resemble a man seen talking to Ms Peake before she boarded the train at Limoges.

According to reports in the French media, Rezala, who comes from the Marseille region, may also have had his name taken for travelling without a ticket on the Brive-Paris train before getting off at Limoges.

The arrest of a suspect would be the first major breakthrough in the Isabel Peake inquiry, which has been criticised in Britain for apparent delays in launching a murder hunt and failing to use techniques deployed in this country.