State Forest and Environment Minister Rockybul Hussain said it had become imperative to ask the premier investigating agency to take charge of the probe in view of allegations that some international gangs were also involved in the poaching incidents.

“My department had written to the Chief Minister on February 6 this year requesting him to ask the CBI to take over the investigations,” Hussain told The Indian Express on Friday night.

“The CBI probe will also clear various doubts expressed by the opposition parties and others in this regard,” he added. A press note issued by the CM’s office, however, said the decision was taken following the sudden spate in rhino killings.

While 21 rhinos were killed by poachers in Kaziranga and two other sanctuaries in Assam last year, the total number of rhinos killed by poachers since 2001 has gone up to 78 after six rhinos were killed this year.

It was only last week that a female rhino and a calf were killed in Kaziranga and two other in the Orang National Park, once again leading to a statewide hue and cry, following which authorities replaced the Divisional Forest Officer directly responsible for protection of rhinos in Kaziranga.

Though forest staff have been able to arrest 143 poachers and also kill 20 since 2001, it has not been able to check the poaching menace.