Pakistan security forces fired volleys of tear gas and rubber bullets Tuesday at thousands of protesters calling for the release of jailed ex-prime minister Imran Khan, after they defied a police lockdown to march inside the nation's capital.

Pakistan's capital, Islamabad, is under lockdown for a second day as thousands of protesters demanding the release of former prime minister Imran Khan from jail converge on the city. His supporters are also calling for the overturning of election results they say were rigged - a claim disputed by the government.