Pakistani police have filed charges against former prime minister Imran Khan, 17 of his aides and scores of supporters, accusing them of terrorism and several other offences after the ousted leader's followers clashed with security forces in Islamabad the previous day.

For hours on Saturday, Mr Khan's followers clashed with police outside a court where the former prime minister was to appear in a graft case.

Riot police wielded batons and fired tear gas while Mr Khan's supporters threw fire bombs and hurled rocks at the officers.

More than 50 officers were injured and a police checkpoint, several cars and motorcycles were torched.

Police said 59 of Mr Khan's supporters were arrested during the violence.

Mr Khan never actually appeared inside the court to face charges that he had sold state gifts received while in office and concealed assets.

Besides Mr Khan, the case filed also accuses former and current politicians, former ministers, a former National Assembly speaker and scores of Mr Khan's supporters.

The charges include terrorism, obstructing police officers in carrying out their tasks, attacks on police, wounding officers and threatening their lives.

The developments are the latest involving increasing violence surrounding the 70-year-old Mr Khan, who was ousted in a no-confidence vote in Parliament last April.

Since then, the former cricket star turned politician has claimed — without offering evidence — that his ouster was illegal and a conspiracy by the government of his successor, Shahbaz Sharif, and Washington.

Both Mr Sharif and the United States have denied the allegations.