The blaze was brought under control and extinguished after few hours, state Fire Services minister Javed Khan, who visited the spot, said.
Fire Services department officials said 25 fire tenders were rushed to the spot after the fire broke out in the seventh floor of the building around 10.30 AM.
"Fire fighters, armed with masks and oxygen cylinders, entered the core area of the fire," a fire brigade officer said adding, there was, however, no reports of any casualty.
On whether police have ruled out any sabotage behind the fire, Ghosh said "Not yet... Unless the final opinion reaches us, we cannot say anything."
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"A team of forensic experts has visited the spot. Our men as well as fire brigade personnel are also there. They are trying to locate what went wrong. We are waiting for their report," Ghosh added.
State Panchayat Minister Subrata Mukherjee, whose office is located in the building, said his room was damaged by the fire.