Academics have criticised the British government for creating a "climate of fear" after the national library declined to store the world's biggest collection of Taliban-related documents over concerns it could be prosecuted under terrorism laws.

A group of international researchers spent years putting together a trove of documents related to the Afghan Taliban, including official newspapers from their time in power, poems, maps, radio broadcasts, and several volumes of laws and edicts -- digitising the estimated two to three million words and translating everything into English.

It was hoped the project, which was launched in 2012 and included members of the British Library on its advisory board, would prove an unprecedented resource for academics and officials trying to understand the movement and the ongoing insurgency in Afghanistan.