Pakistan's former Prime Minister Imran Khan has secured an extension to his protective bail until May 31, as an official announced people involved in violent protests over his arrest would be tried in military courts.

The court extended the bail, which had been due to expire on Wednesday, because the prosecutor requested more time to produce details of the case against him, Khan's lawyer Faisal Chaudhry said on Wednesday.

Khan had been bailed by the Islamabad High Court last Friday following his May 9 arrest, which sparked violent protests across the country that reportedly killed at least eight people.

The arrest of the former prime minister, who was ousted in a parliamentary confidence vote in April last year, has sparked nationwide turmoil in the South Asian nation of 220 million.

Demanding an impartial inquiry

Thousands of Khan supporters had attacked and set on fire scores of government and public buildings, including the army's headquar ters, following his arrest.

On Wednesday the information minister for Punjab province, Amir Mir, said those accused of attacks on the army would be tried by military courts.

Khan, who is facing graft allegations he denies, has disowned those involved in arson, demanding an impartial inquiry.

The military has said the May 9 attacks against the army were "pre-planned" and ordered by Khan party's leaders. Khan has denied the allegation and demanded an investigation.