The fire in the forest area of Mudumalai Tiger Reserve in Nilgiris district is continuing unabated for the third day and has now spread to around 250 acres, officials said.
Over 100 forest department officials and tribals, including children and women of seven villages, were taking efforts to check the spread the fire, forest department sources said.
Following the blaze, entry of tourists into MTR has been banned, they said.
Meanwhile, a helicopter was found flying over the fire ravaged area and department official suspect it could be from Karnataka, where a blaze is raging in Bandipura.