Pakistan’s opposition leader Nawaz Sharif defied house arrest on Sunday to join anti-government protests that quickly descended into violence and chaos, with running battles between stone-throwing protesters and police.

The power struggle between Pakistan President Asif Ali Zardari and Sharif threatens to paralyze the government and distract the nuclear-armed country from its fight against Taliban militants operating along the Afghan border.

“The most operative part (of the evolving situation) is that at a time when terrorists are posing a big threat to Pakistan, the current crisis has weakened the capacity of the Pakistani state and political parties to take meaningful steps to check Talibanization,” security analyst Uday Bhaskar told Mint in New Delhi.

Bhaskar, a former director of the Institute for Defence Studies and Analyses, added that “this has deep implications for India”.

In Lahore, hundreds of police surrounded the Lahore residence of Sharif, a former prime minister, before dawn on Sunday and detained him along with scores of his supporters, a party spokesman said. Officers in the eastern Pakistani city showed party officials an order placing Sharif and his politician brother Shahbaz under house arrest for three days, spokesman Pervaiz Rasheed said. Sharif denounced the order as illegal and later left the house in a convoy of vehicles packed with chanting, flag-waving supporters, headed for a downtown rally that had already turned violent.

“You have seen that the entire country has been turned into a police state. They have blocked all roads, they have used all sorts of unlawful tactics,” Sharif told reporters on the front step of his Lahore home before the rally.

Mobs accompanying the swelling convoy smashed the windows of buses parked along the route. Others torched tyres, sending plumes of black smoke into the blue sky over a usually bustling boulevard littered with stones and empty tear gas shells.

“These are the decisive moments,” Sharif told supporters before he climbed into his car. “I tell every Pakistani youth that this is not the time to stay home; Pakistan is calling you to come and save me.”

Rao Iftikhar, a senior government official, said authorities reconsidered the restrictions on Sharif to allow him to address the rally and return home afterwards. Sharif told Pakistan’s Geo TV network, however, that he would lead a “long march” on Islamabad, the channel said on its website.

The turmoil could not come at a worse time for Pakistan, a central front in US President Barack Obama’s fight against Islamist militancy and facing a wave of Taliban and Al Qaeda-linked violence. The US worries that the crisis will further destabilize the shaky year-old government and prevent it from being an effective ally in the fight against insurgents in Afghanistan.

Analysts warned that a reluctant military, which has ruled Pakistan for at least half its 62-year existence, would be forced to intervene.

“The situation is getting chaotic. It seems violence will take over and compel the army to intervene at some stage,” defence and political analyst Talat Masood told AFP.

Lawyers and opposition party supporters had planned to gather near Lahore’s main court complex before heading towards Islamabad to stage a mass sit-in in front of Parliament, in defiance of a government ban. To thwart them, authorities parked trucks across major roads on the edge of the city, and riot police took up positions outside the railway station and government buildings. Still, several thousands flag-waving demonstrators pushed past police barricades to reach the courts.

Shahbaz Sharif and a host of other protest leaders went underground to dodge their own detention orders. Iftikhar said they had been issued for the head of Pakistan’s main Islamist party and cricketer-turned-politician Imran Khan.

The political turmoil began last month when the Supreme Court disqualified the Sharif brothers from elected office, over convictions dating back to an earlier chapter in Pakistan’s turbulent political history. Zardari compounded the crisis by dismissing the Sharifs’ administration in Punjab, Pakistan’s biggest and richest province, of which Lahore is the capital