Whenever Indian forest guards go to the Susta area, residents tell them they are trespassing into Nepal.

Officials admit that poaching takes place but express helplessness as the territorial dispute is beyond their control.

The Sashastra Seema Bal, a paramilitary force tasked to guard the India-Nepal border, has checkposts in the Susta area, but the territorial dispute limits its effectiveness too.

Experts say Susta has adequate prey base for tigers. The number of big cats can easily increase if protection is provided. The 880 sq. km. Valmiki reserve has 13 tigers, according to a census conducted by the Wildlife Institute of India (WII) in 2006.

S. Kumarasamy, divisional forest officer (DFO) and deputy field director of the Valmiki Tiger Reserve, said: 'The encroachment issue has been there for the past 40 years or so. I have joined here just a few days back. I will only be able to tell you (about the problem) when I go through the latest developments.'

Rajesh Gopal, head of the National Tiger Conservation Authority (NTCA) that manages the 37 tiger reserves in the country, said: 'The post of the field director there had been lying vacant for the past one year. Only recently has a new director joined.'

Sinha said some 140 villages, which are within five kilometres of the park boundary, exert additional pressure on the wildlife by grazing cattle and collecting fuelwood.

The reserve is also home to leopards, fishing cats, chital, sambar, hog deer, blackbuck, sloth bears and rhesus monkeys, among others.

The Valmiki sanctuary is the 18th tiger reserve in the country. It was declared a national park in 1989.

(Sanjeeb Baruah can be contacted at sanjeeb.b@ians.in)