Shibaji Panja, an associate of Bengal chief minister Mamata Banerjee who accompanied her to Bangladesh, was detained at the Kolkata airport on his return on Saturday night.
Panja is a businessman who has become increasingly close to the chief minister over the past years and is often seen around her in various programmes.
According to sources, he was detained at the airport's immigration counter after he returned to Kolkata with the CM's entourage, and then handed over to the NSCB airport police station.
A team of Delhi Police will take charge of Panja.
Delhi Police had issued a lookout notice on February 19. They are looking for him in an economic offence case, the details of which were not available till early morning on Sunday.
Panja had interests in news television channels. A member of the Kolkata International Film Festival committee, he is also believed to be one of prime organisers of the exhibitions of the chief minister's doodles.
Panja's arrest will add to the embarrassment of the Bengal CM. Senior Trinamool Congress leaders have faced interrogation in the Saradha case and one of her ministers is in jail in connection with the multi-crore chit fund scam.
The chief minister has always maintained that the Centre is out to corner her politically using various arms of the law enforcing and investigation agencies.