A murder investigation is under way after the discovery of a burnt body in shrubland on a motorway embankment in Warwickshire.

Police said the victim – a man aged between about 45 and 75 – had suffered substantial head injuries.

The body was found after a driver reported seeing flames by the eastbound M45 near Rugby on Tuesday afternoon.

A post-mortem examination revealed the man was dead when his body was dumped and set alight. The motorway was closed last night as 15 police officers did a fingertip search on a six-mile stretch of the carriageway.

Detective Superintendent Adrian McGee, who is leading the investigation, said officers were examining CCTV footage of the motorway. He said: “I would appeal for anyone who was on the M45 on Tuesday between 12.30pm and 1.30pm to contact the incident room which has been set up. Specialist officers are continuing with a meticulous search at the scene of this incident and on a stretch of motorway either side of the scene and the surrounding area.”

Firefighters were called to the scene at about 1.15pm on Tuesday. They discovered the body and alerted police.

The M45 was closed in both directions between the A45, near Rugby, and its link to junction 17 of the M1.

A spokesman said detectives remained “open-minded” to the motive behind the death. The victim has yet to be identified. “Police would also like to hear from anyone who has concerns for the whereabouts of a male friend or relative aged between 45 and 75 years who has not been seen recently.”

The witness was travelling westbound and the body was dumped on the eastbound carriageway near Dunchurch, police said. Anyone with information should contact the police (01926 415791 or 01926 415789), or anonymously on Crimestoppers on 0800 555111.