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.

Pakistani authorities arrested over 4,000 supporters of Imran Khan, including five parliamentarians, ahead of a rally demanding the release of the former prime minister from prison, where he has been held for over a year.