The CBI has issued a lookout circular (LoC) against former Kolkata Police Commissioner Rajeev Kumar for his role in the multi-crore Saradha chit fund scam, officials said on Sunday.

The agency issued the circular this week alerting all airports and immigration authorities not to allow the IPS officer to leave the country for a year and to detain him if he tries to travel abroad, they said.

The Central Bureau of Investigation (CBI) wants custodial interrogation of Kumar.

LoC is issued against a person directing the immigration authorities to ensure that he or she does not leave India through an airport or by sea.

The 1989-batch IPS officer is accused of being involved in tampering of evidence and attempting to protect certain politicians from investigation into the Rs 2,500-crore Saradha chit fund scam when he headed the Special Investigation Team (SIT) of West Bengal Police.

The CBI later took over the case.

The SIT was formed by the Mamata Banerjee government in 2013. In 2014, the apex court transferred the case to the CBI.

The CBI had told the Supreme Court that it wanted custodial interrogation of Kumar as there was prima facie evidence that he tried to protect the accused.

Earlier, the Supreme Court had vacated its order granting protection to Kumar from arrest. Now, the apex court has allowed the CBI to "act in accordance with law".

The CBI questioned Kumar for nearly five days in Shillong from February 9.

The Saradha group of companies duped lakhs of customers promising higher rates of returns on their investment, the CBI has alleged.

The Election Commission on May 15 relieved Kumar from his post of ADG CID in West Bengal following violence in Kolkata, asking him to report to the Ministry of Home Affairs the next day.