The Pakistan supreme court has set up a judicial commission to investigate a secret memo scandal that threatens the federal government.

The scandal centres on a memo allegedly sent in May to Admiral Mike Mullen, chairman of the US joint chiefs of staff at the time, asking for help in stopping a supposed army coup following the Navy Seals raid in May that killed Osama bin Laden, the al-Qaeda chief.

The scandal first erupted in October when Mansoor Ijaz, a US businessman of Pakistani origin, wrote a column in the Financial Times newspaper claiming that Husain Haqqani, the US ambassador in Washington, drafted the memo and asked him to send it.

Asma Jahangir, Haqqani's defence lawyer, discusses the supreme court ruling in interview to Al Jazeera from Lahore, Pakistan.