The Pakistan government arrested hundreds of opposition activists Wednesday and banned protests in Punjab and Sindh provinces ahead of a planned countrywide “long march” of lawyers led by former prime minister Nawaz Sharif on the issue of restoring Supreme Court judges sacked two years ago. The looming confrontation between the one-year-old government of President Asif Ali Zardari and the opposition raised the prospects of another regime change or a return to military rule. “It's a defining moment for Pakistan,” opposition leader Sharif told a rally Wednesday in North West Frontier Province. “This is an opportunity to save Pakistan ... promise me that you'll fight this battle for the survival of Pakistan” he said. The protesters' convoy of cars and buses is due to set off in the southern provinces of Sindh and Balochistan on Thursday and reach Punjab on Friday. They aim to begin a sit-in outside parliament in the capital, Islamabad, on Monday. Police were seen preparing shipping containers, which are used to block roads, in the city of Rawalpindi, adjacent to Islamabad, witnesses said. The government has threatened to prosecute Sharif for sedition if violence erupts during the protest. It has also said the rally will not be allowed into central Islamabad but organizers can use open ground on the city's outskirts. The activists are pushing for the reappointment of former Supreme Court chief justice Iftikhar Chaudhry who then army chief and president Pervez Musharraf had dismissed in 2007. If reinstated, Chaudhry may reopen corruption charges against Zardari, which Musharraf had dropped in a deal that saw former prime minister Benazir Bhutto and her husband Zardari returning from exile in late 2007. Bhutto was assassinated shortly after her return. Army chief Gen. Ashfaq Parvez Kayani, who has given Zardari an ultimatum “to clear up the mess” by March 16, met Gilani on Wednesday, according to a statement from the premier's office. It gave no details of their discussion. A spokesperson of Zardari's Pakistan People's Party (PPP) rejected as “absolutely false and mischievous” rumors that the army has asked the president, who is visiting Tehran, to head for Dubai, where he has a home, and not return to the country. A senior police official said nearly 400 people had been picked up across Punjab – around 350 of them in Lahore – under a law that allows for six months imprisonment. Those rounded up include members of Sharif's party, who has been disqualified from contesting elections. A top leader in Sharif's Pakistan Muslim League-N (PML-N), Raja Zafarul Haq, was placed under house arrest, police said. Many lawyers and MPs have gone into hiding . Media reports said Sharif could be put under house arrest. Raja Zafar-ul-Haq, chairman of Sharif's party, said police had put him under house arrest at his Islamabad home. An arrest warrant has also been issued against cricketer-turned-politician Imran Khan, chief of the Tehrik-e-Insaaf party. Khan's private secretary has been arrested and police are searching for Khan, who lives just outside Islamabad. Aitzaz Ahsan, a lawyer's movement leader, said he believed “hundreds” of lawyers had been arrested, but insisted the movement – which helped bring down the government of Musharraf – would not falter. “How long can the state resist?” he told a local TV station. “We will keep on knocking on the door of Islamabad relentlessly.” “At the moment what we are witnessing ... indicates this government has shades of autocratic rule,” Zaffar Abbas, a prominent journalist and commentator, told Dawn News television. In Washington, Democratic Senator John Kerry said Wednesday that the United States must do what it can to “sustain the democracy” in Pakistan amid angry public protests against the government. Britain's British High Commissioner to Pakistan, Robert Brinkley, held talks with Gilani as the mission said it was “very concerned” about the reported arrests. __