The rally has been declared illegal and Islamabad is under lockdown [EPA] 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.

Thousands of supporters of Pakistan’s imprisoned former premier Imran Khan have defied a lockdown and mass arrests to head to the capital to demand his release.

Clashes erupted in Islamabad as Pakistan Tehreek-e-Insaf supporters, led by former premier Imran Khan's calls, entered the capital. The confrontation resulted in a policeman's death, numerous injuries,