Huge crowds of villagers following a wild elephant that has been stranded in Bangladesh for more than a month by floods are hampering efforts to rescue it, forest officials say.

Severe floods in the north-eastern Indian state of Assam separated the four-tonne female elephant from its herd as strong currents in the Brahmaputra river washed it across the border to northern Bangladesh late June.

This week Indian wildlife officials travelled to Bangladesh to join local forest rangers and vets to rescue the animal, which is now struggling to stand on its feet after a journey of more than 100 kilometres.

"It's now standing in … [1.5-metre-deep] floodwater in Jamalpur district. It is extremely weak. There are more than 10,000 people watching her from a close distance," Bangladeshi vet Sayed Hossain said.

Mr Hossain said the crowd was hampering its efforts to reach higher ground as "thousands of villagers have been constantly following the animal", even at night.

Forest official Tapan Kumar Dey said a team had brought a dart gun, crane and lorry to carry the animal once it reaches dry ground and can be tranquilised — but the operation could not be carried out while the elephant is in water.

"Her condition is very bad. Last night it travelled 12 kilometres, but it mostly avoided dry ground because of presence of so many people," Mr Dey said.

A trained elephant was being brought to the scene in a desperate attempt to lure the wild animal away from the water.

"It is so weak that it can't even lift its trunk. You can see her ribs from a distance," Ritesh Bhattacharjee, a visiting Indian forest official, said.

The rescue bid comes days after Indian wildlife officers appealed for help in caring for eight rhino calves pulled from the floodwaters in Assam.

Scores of people die every year from flooding and landslides during the monsoon rains in India and neighbouring Nepal and Bangladesh.

So far this year 96 people have died in the worst-hit Indian states of Assam and Bihar while 41 people have died in downstream Bangladesh.

AFP