Police baton-charged activists and manhandled dozens into vans in Karachi Thursday, as thousands defied the government in a mass protest that has thrown the country into crisis. Lawyers in black suits and opposition party activists carrying flags and punching their fists in the air marched in Pakistan's biggest cities of Karachi and Lahore, demanding that President Asif Ali Zardari reinstate sacked judges. Organisers hope that hundreds of thousands of lawyers, opposition supporters and civil activists will join a four-day convoy on the 1,500 kilometres (940 miles) route from Karachi to Islamabad, where it is intended to arrive Monday. In the third such annual march in Pakistan, protesters want Zardari to act on a promise to reinstate judges after former military ruler Pervez Musharraf sacked around 60 of them, including the Supreme Court chief justice, in 2007. Main opposition leader Nawaz Sharif, locked in a showdown with Zardari, has urged the masses to rise up against the weak civilian government, which is struggling with a political crisis, the economic meltdown and Islamist violence. A nervous government banned all protests in Punjab, the country's most important political heartland, and Sindh, the province including Karachi, where security forces guarded key installations amid fears of violence.