Abdul Hai, 61, former sub-inspector attached to the Passport section, was arrested from his residence in North 24 Parganas around 11.45 pm, they said, adding that he has been sent to police custody till January 18.

“He (Abdul Hai) had been posted in the department for several years. A bank transaction has been found with one of the accused. We need him for further interrogation as we need to know who all are involved and how big this racket is,” Chief Public Prosecutor Sourin Ghosal submitted in court.

According to the police, the accused had given clearance to 51 passports which were made with fake documents and for each passport he charged Rs 25,000.

With Hai’s arrest, the police have so far apprehended nine people in the racket, the police said.

According to the police, the racket functioned in the guise of a travel agency and had illegally issued 73 fake Indian passports to infiltrators, particularly Bangladeshi citizens.

Earlier, the Kolkata police nabbed Dhiren Ghosh, 48, from his rented house at Madanpur of Chakdaha in Nadia on Tuesday night and also seized several documents.

Sources said Ghosh’s name cropped up while interrogating Manoj Gupta, one of the masterminds of the racket who was arrested recently.

The police had also apprehended other members of the racket, including a college student Ripan Biswas and his father Samaresh. The other arrested are Mukhtar Alam, Tarak Nath Sen, and Dipankar Das.