ISLAMABAD, Pakistan – Pakistan agreed Monday to reinstate a fired chief justice, a government official said, a move that could help defuse a political crisis that has sparked street battles and raised fears of instability in the country at a time of surging Islamist violence.

Opposition leaders and lawyers had vowed to sit-in at the parliament later Monday until Iftikhar Mohammad Chaudhry, known for his independence and willingness to challenge authority, was reinstated. The capital has been barricaded and scores of extra police brought in amid fears of violence.

“Yes, the chief justice is going to be restored,” said a senior government official, who spoke on condition of anonymity because the prime minister was due formally announce the decision later Monday. He said Chaudhry would be sworn in on March 22, the day after the current chief justice was due to retire.

Presidential spokesman Farhatullah Babar said Prime Minister Yousuf Raza Gilani would soon have “good news” for the country that would “end the crisis.”

The concession came as thousands of protesters led by Nawaz Sharif, the head of the largest opposition party and a longtime foe of President Asif Ali Zardari, were traveling to Islamabad in a convoy to join the planned sit-in. Sharif joined the convoy after ignoring a house arrest order in his hometown of Lahore in Punjab, where his supporters fought running battles with police.

Party spokesman Pervaiz Rasheed said it had received confirmation of the government’s decision to restore Chaudhry from “its messengers” and said Sharif would address supporters after Gilani’s address, following which the convoy would return to Lahore.

Chaudhry was fired by former President Pervez Musharraf in 2007 after he took up cases challenging his rule, sparked a wave of protests that helped force Musharraf from power in 2008.

Musharraf’s successor, Zardari, pledged to reinstate Chaudhry within 30 days of taking office, but reneged on the promise, apparently out of fear the justice might target him for past corruption cases.

Lawyers and civil rights activists remained committed to the cause of Chaudhry’s reinstatement, believing it was a vital first step in getting an independent judiciary in Pakistan. The court system has often been abused by past rulers to cement their grip on power. It was not clear whether Zardari, who has immunity from criminal prosecution as president, had secured any guarantees to address those fears.

Lawyers and civil rights activists remained committed to the cause of Chaudhry’s reinstatement, believing it was a vital first step in getting an independent judiciary in Pakistan. The court system has often been abused by past rulers to cement their grip on power.

Their movement got a boost last month when Sharif threw his full weight behind it after he and his brother, Shahbaz, were banned from elected office by the Supreme Court. Zardari then dismissed the government led by Shahbaz in the Punjab province, the wealthiest in Pakistan and a vital prize for politicians.

On Saturday, the government said it would appeal the Supreme Court ruling.

In recent days, U.S. officials, including Secretary of State Hillary Rodham Clinton, had spoken to Zardari and Sharif, urging them to reach a deal. Washington and other Western capitals had been concerned the crisis was distracting the nuclear-armed country from its fight against Taliban and al-Qaida militants operating along the Afghan border.

The early morning announcement capped a day of high drama.

Before dawn, hundreds of police surrounded Sharif’s residence in Lahore, carrying an order for his house arrest. Sharif denounced the order as illegal and later left the house in a convoy of vehicles as police stood by. It was unclear why they relented, but Lahore is Sharif’s political stronghold.

Some of the protesters defied police barricades to gather near the city’s main courts complex and pelt riot police with rocks. One mob smashed the windows of buses parked along the route of Sharif’s convoy, while another broke into the main Post Office building, trashing furniture and then clambering onto the roof to hurl rocks at police below.

Police responded with tear gas, and beat several protesters with batons. Associated Press reporters saw several injured officers being helped away. A handful of protesters were detained and bundled into police vans.

Later, the crowd swelled to several thousands and police again pulled back. Many were black-suited lawyers, but most appeared to be supporters of Sharif, equipped with party flags and chanting “Go Zardari go!”

For days, the government has been seeking to squelch the protest movement.

Authorities have put the army on alert and temporarily detained hundreds of activists nationwide to prevent them traveling to Lahore or Islamabad. But its resolve appeared to waver Sunday amid signs of internal party dissent. A day earlier, a prominent minister quit Zardari’s Cabinet, apparently over attempts to censor critical media coverage.

The Sharifs and 16 other protest leaders were initially ordered under house arrest, said Rao Iftikhar, a senior government official. Later, he said authorities reached an “understanding” with Sharif that he would address the protesters in Lahore and then return home — an arrangement that authorities failed to enforce.

Sharif accuses Zardari of being behind the Supreme Court ruling last month that disqualified put Sharif and his brother from elected office over convictions dating back to Musharraf’s rule.

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Associated Press writers Babar Dogar in Lahore, and Zarar Khan and Asif Shahzad in Islamabad contributed to this report.