Kolkata: Narcotics Control Bureau (NCB) seized ephedrine hydrochloride, a psychotropic substance used for manufacturing heroin, from the salt lake residence of former Central Bureau of Investigation (CBI) additional director (East) U N Biswas.

NCB assistant director N C Patra said that five persons -- three of Myanmarese and two of Chinese origin -- who were ground floor tenants of Biswas' residence, have been arrested and were produced at the Sub-divisional Judicial Magistrate's court at Barasat.

The seized matter has been valued at Rupees five crore in the international market, Patra said.

To a question, the NCB Assistant Director said the former CBI additional director was being interrogated by NCB sleuths.

Biswas had pleaded ignorance about the activities of his tenants and said those who referred them to him had not mentioned anything about their possible involvement with psychotropic substances, Patra added.

PTI