Islamabad, Pakistan – Imprisoned former Prime Minister Imran Khan has urged his supporters to “fight till the end” as Pakistani authorities cracked down on protesters calling for his release.

Security forces on Tuesday clashed with supporters of Khan’s Pakistan Tehreek-e-Insaf (PTI) party who broke through barriers as they marched towards the centre of the locked-down capital, Islamabad, in an attempt to stage a sit-in.

The protesters are demanding the return of what they call a “stolen mandate” after February’s elections, the release of political prisoners and the reversal of a constitutional amendment that allows a civilian government to call in the army to help it implement “law and order”.

In a post on social media, Khan told protesters to remain peaceful and united, saying their struggle is for Pakistan’s “survival and true freedom”.

As tensions rose, the government dismissed prospects of “further dialogue” with the PTI and accused Khan’s wife, Bushra Bibi, of orchestrating the unrest.

“The loss of life and economic damage over the past few days lies squarely on one person’s shoulders,” Interior Minister Mohsin Naqvi said at a news conference on Tuesday evening. “She is wholly responsible for this chaos.”

Led by Bibi, who was recently released from prison after nearly nine months of incarceration, a PTI convoy departed on Sunday from Khyber Pakhtunkhwa, a PTI-controlled province in the northwest, with the goal of reaching the capital.

Despite facing a number of obstacles, including highway closures and shipping containers blocking roads, hundreds of PTI supporters on Tuesday morning reached D-Chowk, a site in Islamabad’s highly fortified Red Zone, which houses key government offices – including the presidency, the prime minister’s office, the National Assembly and Supreme Court – as well as the diplomatic enclave.

Initially, the security personnel present at the site withdrew, allowing the crowd to climb onto containers, chanting slogans and waving PTI flags.

However, members of the Rangers paramilitary unit soon replaced the police and responded with live fire and tear gas, covering the area in thick smoke and forcing the protesters to scatter. The PTI said two people were killed.

Paramilitary soldiers fire rubber bullets to disperse Khan supporters in Islamabad [Irtisham Ahmed/AP Photo]

As night fell, authorities shut off streetlights, plunging the area into darkness and raising fears of a large-scale operation against the protesters.

The PTI convoy was stationed fewer than 3km (almost 2 miles) away from D-Chowk.

Internet connectivity, meanwhile, has remained patchy throughout the day for users across the city with mobile data services completely inaccessible.

Bibi, who has so far maintained an apolitical but an influential presence in Khan’s life, delivered a number of short speeches throughout the day, urging PTI supporters to stand firm.

“Our protest will not end till Imran Khan is amongst us and tells us what to do next,” she told supporters, encouraging them to move towards D-Chowk.

Earlier in the day, Naqvi, the interior minister, hinted at Bibi when he alleged that a “hidden hand” was sabotaging peaceful resolution efforts and pushing an antistate agenda.

“Their entire leadership is keen on having peaceful dialogues, but there is one hidden hand which is controlling the decision-making and has an anti-Pakistan agenda. In my experience, that hidden hand is the root cause of all this chaos,” Naqvi told reporters on Tuesday morning.

Meanwhile, Prime Minister Shehbaz Sharif has remained largely silent on the ongoing protests.

His only public action on Tuesday, besides meeting visiting Belarusian President Aleksandr Lukashenko, was to attend the funerals of three Rangers who were killed in a hit-and-run incident on Monday evening

The government has accused the PTI supporters of being behind the deaths, a claim the party has vehemently denied. Separately, authorities said, a police officer also died in clashes with protesters on Monday as they were approaching Islamabad.