Pakistan's former Prime Minister Imran Khan's jail detention related to charges of leaking state secrets has been extended for another two weeks, his lawyer says.

The 70-year-old former cricket star has been at the centre of a political crisis since he lost a confidence vote in parliament in April 2022, and his conviction in a separate corruption case last month resulted in him being barred from contesting a national election due to be held in coming months.

In late August, a high court suspended Khan's prison sentence for corruption just weeks after he was jailed, but a prior order for his remand in custody in the state secrets case prevented his release.

The latest extension of the remand order will keep Khan in jail until September 26, lawyer Naeem Panjutha said on Wednesday in a post on messaging platform X, formerly known as Twitter.

In the state secrets case, Khan is charged with making public the contents of a confidential cable sent by Pakistan's ambassador to the United States and using it for political gain, according to a Federal Investigation Agency (FIA) document seen by Reuters.

Khan alleges the cable proves the US had pressed Pakistan's military to orchestrate the fall of his government because he had visited Russia shortly before its invasion of Ukraine in February 2022.

Washington and the Pakistani military have denied Khan's accusations.

In the corruption case, Khan was sentenced to three years in jail for unlawfully selling state gifts during his time as prime minister from 2018 to 2022.

As a result, the election commission barred him from contesting elections for five years, and although the prison sentence was suspended last month the conviction still stands.