Superintendent Dutt, CBI inspector Rajesh Chandra Karnatak, alleged middleman Rajesh Pachisia and businessman Dinesh Chand Gupta were produced before the court where CBI sought seven days police custody of the four accused.
"All the accused are remanded in CBI custody till 21 May," Special CBI Judge V K Gupta said.
Dutt, however, claimed innocence and alleged a conspiracy has been hatched to keep him out of the Supreme Court-monitored Coalgate probe team.
CBI said Dinesh Gupta had a land dispute and a cheating case was registered against him at Amar Colony police station here and Dutt used to pressurize the Delhi Police officials, who were investigating the cheating case, to quash the FIR and for this he had demanded Rs 15 lakh from Gupta.