Four security force members were killed in Pakistan's capital, Islamabad, on Tuesday, the country's Interior Ministry said, after thousands of supporters of imprisoned ex-Prime Minister Imran Khan defied a police lockdown to march in the city center.

Police fired tear gas and rubber bullets as the protesters broke through a barricade of shipping containers blocking off the national capital. The government warned that security forces would respond with live gunfire if protesters used weapons against them.

Prime Minister Shehbaz Sharif said four members of the paramilitary Rangers force died after being "run over by a vehicle." There were no claims of responsibility for the attack.

Scores of people have been wounded in two days of clashes, including journalists who were attacked by Khan supporters, reports said. 

The protesters are responding to Khan's call for a sit-in demonstration near the parliament to push demands ranging from their leader's release to the government's resignation.

Protesters defy Islamabad lockdown

Islamabad has been under a lockdown since late Saturday.

Mobile internet in the city has been partially severed and over 20,000 police personnel have been deployed on the streets, many of whom are armed with batons and riot gear.

However, convoys of Khan's Pakistan Tehreek-e-Insaf (PTI) party have traveled to Islamabad from the party's power center in the northwestern Khyber Pakhtunkhwa province and the most populous province of Punjab, hauling aside roadblocks.   

Khan has been in jail for over a year. 

The 72-year-old charismatic former cricketer, who served as prime minister from 2018 to 2022, faces over 150 criminal cases.

PTI claims the charges are politically motivated.

Meanwhile, Prime Minister Sharif on Tuesday denounced the clashes as being aimed at achieving "evil political designs."

"It is not a peaceful protest. It is extremism," he said in a statement issued by his office.

On Monday, authorities said that at least one policeman was killed and dozens others were injured in clashes outside of Islamabad as the protesters were closing in on the capital.

dvv/nm (AFP, AP, Reuters)