ISLAMABAD: Former Pakistan Prime Minister Imran Khan arrived at an Islamabad court on Friday under heavy security cover as his supporters clashed with police elsewhere in the city, broadcaster Geo TV reported.

Television footage showed heavily armed paramilitary troops and police outside the Islamabad High Court as Khan was brought in a motorcade of nearly a dozen vehicles.

Khan, wearing dark glasses and dressed in a sky blue shalwar kameez, the loose shirt and trousers popular in Pakistan, walked into the court surrounded by lawyers and security forces, the broadcaster said.

Geo said supporters of Khan clashed with police elsewhere in the city as roads were cleared for his convoy. The Islamabad police have imposed an emergency order banning all gatherings in the city.

Khan's Pakistan Tehreek-e-Insaaf (PTI) party said thousands of "peaceful Pakistanis" will gather in Islamabad in solidarity with their leader, who police said was allowed to meet 10 people on Thursday night in a police guesthouse.

His arrest earlier this week, which sparked deadly unrest in the nuclear-armed nation, was ruled "invalid and unlawful" by the Supreme Court on Thursday.

The top court ordered him to appear before the Islamabad High Court for a hearing on his petition challenging the anti-corruption action against him.

Violence sparked by Khan's arrest has aggravated instability in the country of 220 million people at a time of severe economic crisis, with record high inflation, anaemic growth and delayed IMF funding.

Nearly 2,000 people have been arrested for violence since Khan's detention on Tuesday and at least eight have been killed.

Protesters have attacked military establishments, ransacked the house of a top army general in the eastern city of Lahore, and set ablaze state buildings and assets in other places.

Khan was arrested a day after the powerful military rebuked him for repeatedly accusing a senior officer of trying to engineer his assassination and the former armed forces chief of being behind his removal from power last year.

The army has warned Khan's supporters that it will respond firmly if there are further attacks on its assets, saying in a statement on Wednesday that the violence at its installations was "pre-planned" and ordered by his party leadership.

Khan's party has maintained it has only called for peaceful protests.