The directive was signed by the deputy inspector-general of forests (wildlife), M.L. Srivastava, last month after the ministry reviewed the report of the sub-committee on guidelines for roads in the protected areas of the country.

The sub-committee was constituted in 2013 under the chairmanship of M.K. Ranjitsinh, a member of the National Board for Wildlife.

Speaking to The Telegraph, Prerna Singh Bindra, a former member of the board's standing committee, said it was "excellent news" that the government had taken on board all recommendations of the sub-committee, including not allowing roads, which she said were "agents of doom for wildlife", in the protected areas.

"Besides wildlife mortality by accidents, roads fragment habitat and bring in ancillary development. However, I notice that there still remains scope for widening roads within protected areas, which can have equally grave consequences for wildlife. Protected areas, which cover less than 5 per cent of the country, are heavily stressed and must remain sacrosanct if we are to conserve wildlife," she said.

The ministry's directive says proposals to widen existing roads, if "unavoidable due to reasons of purpose and alignment", can be placed before the board's standing committee, which shall consider such cases in view of the feasibility of mitigation measures irrespective of cost.

A source, however, said, "There is no definition of unavoidable as these days projects are being cleared on the pretext of being unavoidable."

Former additional director-general (wildlife), ministry of environment, forests and climate change, Jagdish Kishwan, said, "It is an unprecedented decision and will have good implications".

The subcommittee in its report said, "Roads in protected areas break forest contiguity, impinge on forests and well-worn migratory paths of animals, break tree cover and canopy and slice vegetation - all of which gravely impacts wildlife. Unless great vigilance and checks are provided, roads provide conduits for illegal extraction of timber and forest produce and for poaching, particularly at night, from vehicles."

"This is a good move and the authorities can now plan accordingly," Firoz Ahmed, member of forest advisory committee, said.

Wildlife conservationist Bittu Sahgal told this correspondent: "The decision is good but I doubt whether even the smallest road can actually be stopped by the ministry, given the all-out war declared on our bio-diversity vaults by the advisers to Prime Minister Modi."

Assam was one of the states that had diverted the proposed expansion of National Highway 37 through Kaziranga National Park in 2008, arguing that it would adversely affect the park's animals and rich biodiversity, despite protests from locals.