Hundreds of conservationists have begun a major survey of the number of endangered Royal Bengal tigers living in a vast forest region bordering Nepal and India, officials said Tuesday.

Wildlife experts are monitoring images from hundreds of cameras set up in protected areas of the Tarai Arc Landscape, a mainly forested area which stretches for some 950 kilometres (600 miles), in the four-month survey.

"We are conducting a survey on the tiger's occupancy and behaviour. The results will help us identify the animal's paths and prey," said Megh Bahadur Pandey, director general of Nepal's Department of National Parks and Wildlife Conservation.

"In 2011 and before that, we conducted surveys of tigers in some national parks but this is the first nationwide survey in five years," he said, adding that a parallel survey was being conducted in India.

"The census results will enrich our understanding. If we find that the number has increased, then we will know the reasons. In case the population is on decline, the survey will help us develop effective strategies," he said.

Ghanashyam Gurung, conservation programme director for Nepal at the conservation group WWF, said it was the first time that officials from Nepal and India had worked together to get a full picture.

"India and Nepal used to conduct surveys without consulting each other, but this census will provide us with the data from both sides," he told AFP.

"The census will show us the total population of Royal Bengal tigers that roam the Tarai Arc Landscape, which is one of the world's biggest concentrations of tigers."

The WWF says tigers worldwide are in serious danger of becoming extinct in the wild. Their numbers have fallen from 100,000 in 1900 to around 3,200 now.

There are around 1,850 Bengal tigers living in the wild, including around 1,400 in India and around 150 in Nepal, the WWF says.