At least one policeman has been killed and more than 50 injured, Pakistan’s authorities say, as officials try to stop thousands of opposition protesters reaching Islamabad.
Scores of supporters of jailed former PM Imran Khan have been arrested and the capital is under lockdown for a second day.
Khan has been detained for more than a year on various charges, but remains hugely popular despite his legal troubles.
His wife, Bushra Bibi, told supporters on Monday the march would continue until her husband was freed.