Pakistan police said Wednesday they had arrested nearly 1,000 protesters who marched on the capital demanding the release of jailed ex-prime minister Imran Khan, after crowds were evicted from the city centre in a sweeping security crackdown.

Pakistani security forces have been accused of opening fire on supporters of Imran Khan who stormed Islamabad this week to demand his release. The jailed former prime minister’s aides claimed an unspecified number of people died and hundreds were injured during chaotic scenes on Tuesday night in the heart of the capital.

Mr Khan’s Pakistan Tehreek-e-Insaf (PTI) said a “massacre” unfolded in Pakistan and the armed forces fired live rounds, killing “hundreds of people” and many injured with gunshot wounds. It did not give a number as to how many were killed.