Official sources said India Reserve Battalion (IRB) joined in the operations from the Arunachal Pradesh side in the searches conducted in the border district of West Kameng and in northern part of Rangapara in Assam.
Assam Additional Director General of Police (law and order) A P Rout, who is here to monitor the operation, said the joint search was on but police have no information about the Rs 20 crore ransom demanded by the abductors from Agarwal's family.
The kidnappers were, however, changing their location after contacting Agarwal's family.
The NHPC official was abducted by from Charduar area near Assam-Arunachal Pradesh border on September 21 when he was on his way from Tawang to Guwahati.
Agarwal, who hails from Faridabad in Haryana, is the general manager of 600MW Tawang Chu-I hydroelectric power project.
The militant group has reportedly sent a mail to the NHPC chief general manager demanding a ransom of Rs 20 crore for safe release of Agarwal.
