Thousands of kilometres of railways and roads planned across Asia risk dismantling progress made to save the world’s last tigers, conservationists have warned.

The WWF said an infrastructure boom in coming years will lead to the construction of 11,000km of new transport projects, carving up the big cat’s habitats and stopping them from travelling across the huge ranges they need.

Previous approaches such as stopping poaching and looking after protected areas would no longer be enough to help tigers, WWF said in a report. It said growing human populations and trade are driving a road-and rail-building splurge valued in the trillions.

Tiger numbers have bounced back modestly since an all-time low of 3,200 in 2010, to an estimated 3,890 now. That has been driven partly by a target to double tiger numbers by 2022, set by Vladimir Putin, the then-Chinese premier Wen Jiabao and other leaders of tiger range states.

“The potential impact of the linear infrastructure may be way beyond a setback - this could dismantle the progress we’ve made over 20-30 years,” said Dr Ashley Brooks, a co-author of the report, The Road Ahead. “The scale is astronomical.”

Brooks cited a series of huge national development projects, such as national highway seven in India, which will cut through a critical corridor between two tiger reserves. There are also plans for a transport link between Bangkok and a port slated for Dawei in Myanmar.

In Sumatra, a north-south highway will dissect the whole island, while Nepal is planning a national railway upgrade and work on its “postal highway”, which Brooks said posed a significant threat to a natural corridor for tigers between India and Nepal.

WWF will not try to block such infrastructure, some of which will be four- and eight -lane highways. Instead, it will try to ensure they are built in ways that tigers can still get through them, such as using animal underpasses, elevating roads or tunnelling. “We accept these developments should go ahead but we will lobby with governments so that they avoid as much as possible critical habitats and areas that can’t be lost,” said Brooks.

Not only are the roads direct threats to the tigers and their prey, but they will have knock-on or “cascading” effects, WWF said. “Roads provide access to areas that previously weren’t there. Poachers are the first people behind the road builders,” said Brooks.

While acknowledging that it would be hard to persuade some governments to spend more on making transport infrastructure tiger-friendly, he warned that he consequences would be grim for tigers if they did not.

Brooks added: “If these measures aren’t taken, if governments don’t see the need to maintain connectivity at this kind of scale, and let infrastructure slice and dice these landscapes, you will have little pockets of tigers. They will always need active management. And what we’ve seen before is the numbers will then just contract and contract and contract.”