Pakistan is on high alert as lawyers and anti-government protestors begin a four-day march to demand the reinstatement of 60 senior judges, sacked in 2007 by previous President Pervez Musharraf.The government claims the march is aimed at destabilising the country and police have moved swiftly by arresting hundreds of opposition supporters. The authorities have also banned political gatherings in Punjab and Sindh amid fears of violence. Tensions in the country are high after a court ruling barred opposition leader Nawaz Sharif from holding public office. Sharif has backed the lawyers and called on all Pakistanis to join the demonstration. The lawyers are furious that President Asif Ali Zardari has yet to act on his promise to reinstate the judges. It is a difficult time for the civilian government as it faces severe problems from Islamist militants and a sinking economy.