British police investigating the murder of Indian millionaire Amarjit Chohan believe the two prime suspects in the case may have fled to Spain and have sought the help of their counterparts in that country.

Ken Regan (54) and William Horncy (51) fled across the English Channel last week and are believed to be heading for Spain, a popular destination for international fugitives because of its poor record with extraditions.

A third suspect -- Peter Douglas Rees -- has since been added to the list of wanted men.

Rees (38) is a close associate of Regan alias Avery, and Horncy alias Smith.

Chohan (46), a freight services contractor, disappeared along with his family from his London home in February. His decomposed body was found two weeks ago floating in the sea near the city of Bournemouth.

To his friends and neighbours, Chohan was the proprietor of CIBA freight, a successful fruit and vegetable import business with 22 employees and an annual turnover of £22 million.

Regan, a heavy goods driver employed by Chohan, used to own his own freight company. Horncy is his associate.

Post-mortems have so far failed to reveal the cause of death, but the police believe Chohan was initially buried in a field in the nearby county of Devon before the body was excavated and dumped in the sea.

A five-day excavation of the field has turned up a number of personal items, but the bodies of Chohan's wife Nancy (25), their sons Devinder (18 months) and Ravinder (four months), and mother-in-law Charanjit Kaur (51) are still missing.

Detectives have floated a number of theories to explain Chohan's murder, including revenge, extortion and drugs, but admit they are far from certain about the real reason.

"What is certain is that we have very grave concerns about the welfare of Mr Chohan's family," a police source said.

Nancy's brother Onkar Verma has appealed to the public for help in tracing the family.