Pakistan's Supreme Court says it will investigate the scandal surrounding an unsigned memo seeking Washington's help to rein in the powerful military, a decision that is bound to pile pressure on the weak civilian government.

Pakistan's then ambassador to the United States, Husain Haqqani, has been accused of writing the memo on behalf of the government after U.S. forces found and killed Osama bin Laden in Pakistan in May.

He denies involvement but has resigned pending an investigation.

(Reporting by Faisal Aziz; Writing by Qasim Nauman; Editing by Nick Macfie)