U.S. and British diplomats were scrambling to broker a truce between Pakistan’s feuding political leaders tonight as thousands of black-suited lawyers defied a government ban to launch a mass protest across the country.

Richard Holbrooke, the new U.S. special envoy for Pakistan and Afghanistan, telephoned Asif Ali Zardari, Pakistan’s president, to discuss the unrest, which has raised fears that the army could take power once again.

"Mr Holbrooke conveyed the anxiety of the U.S. administration over the worsening political crisis and asked the president to find ways to end the strife," a senior Pakistani official told The Times.

David Miliband, the foreign secretary, also spoke to Mr Zardari as lawyers and opposition activists clashed with police at the start of a "long march" from major cities towards Islamabad, the capital.

Organizers hope that hundreds of thousands will join the march, due to end with a rally in front of the national parliament on Monday, to demand that the government reinstate judges deposed under Pervez Musharraf, the former president.

Nawaz Sharif, the former Prime Minister whose party quit the government last year over the same issue, has urged Pakistanis to join the march and to rise up against their weak civilian government.

The government responded by banning protests in the provinces of Punjab and Sindh, detaining more than 300 activists on Wednesday and arresting dozens more today.

The United States and Britain now fear that further unrest could undermine the Pakistani army’s efforts to fight Al Qaeda and Taliban militants in Pakistan’s northwest, or even force it to take over the government again.

Click here to read the full report from Times Online.