An international search involving Interpol has been launched to locate a wealthy London-based Indian family that has gone missing for the last six weeks.

The police suspect that smugglers may have abducted them.

Amarjit Chohan (46), a well-known figure in the Asian community in Southall, West London, his wife Nancy (25), their two sons and his mother-in-law vanished without explanation from their home in Heston, West London on February 16.

Chohan owns a fruit and vegetable import and distribution company called CIBA with a 5-million-pound turnover a year.

Nancy's brother Onkar Verma, who lives in New Zealand, first raised the alarm when his sister stopped calling him. He said he was very concerned about what had happened to them.

"I am extremely worried for their safety. It is extremely unusual and out of character for Nancy to go missing and to hear nothing from her or my mother," Varma (28), said after arriving in London.

Police alerted Interpol to the family's disappearance and asked forces across Europe and India to be alert for anyone matching the Chohans' descriptions crossing borders.

Police investigating the firm's operations fear that criminals might have been using it to smuggle 'khat' into the United States.

Khat leaves have an effect similar to amphetamines. The shrub is grown in Somalia and East Africa and is not illegal in Britain.