Forest officials of the Sunabeda Wildlife Sanctuary in Nuapada district boycotted the tiger census fearing danger to their live as they suspected a large number of Maoists have entered the sanctuary.

"That the Maoists are roaming freely inside the sanctuary area was alleged by forest personnel who boycotted tiger census on May 8. I have already informed the state government about the allegation," Orissa's chief wildlife warden P N Padhi told PTI.

The forest officials suspected that a large number of dreaded ultras from neighbouring Chhattisgarh had entered into the sanctuary area after Dantewada massacre on April 6.

The fear of forest personnel stems from the recent killing on April 29 of one Sangram Swain, a forest guard inside the sanctuary.

Home department must be aware if there are Maoists inside the sanctuary, said forest secretary U N Behera.

The Sunabeda Wildlife Sanctuary, comprising 15 revenue villages and home to about 15,000 ethnic tribes belonging to Chakuita, Paharia and Bhunjiya tribes, had witnessed several Maoist violences in the past.

The sanctuary, spread over 600 sq km in Nuapada district bordering Chhattisgarh, witnessed Maoists hoisting black flag in sanctuary area on Independence Day, 2009.

The Maoists had in the past struck twice killing a member of anti-poaching squad Kirish Rout in Kutrabeda on the night of November 15 and former ward member of Sunabeda GP Chandar Singh Barge between Sunabeda and Gatibeda on the night of November 17 last year.

"They have warned us several times not to erect the gate at Cherechuan which had been razed by them," said a forest official.

On June 22, 2009, the ultras had demolished the forest gate and assaulted forest guard Nuapan Majhi and anti-poaching staffer Mansingh Sabaria before fleeing into the forest.

The ultras had also issued similar threats at a forest gate located on the southern side of the sanctuary at Bharuanmunda. Forest guard Jhasketan Seth reportedly received the threat, police records said.