Parliament's intelligence watchdog is to investigate the decision to launch an RAF drone strike in Syria which killed two British nationals fighting for Islamic State.
21-year-old Reyaad Khan from Cardiff was one of the men killed by the strike in August.
Dominic Grieve, the chairman of the Intelligence and Security Committee (ISC) which oversees the work of MI5, MI6 and GCHQ, said they would be examining the "intelligence basis" for the action.
At the same time, the new chairwoman of the Joint Committee on Human Rights, former Labour deputy leader Harriet Harman, announced that their first inquiry would be into "government drone strikes".
David Cameron told the Commons last month that he had authorised the strike on the grounds that one of the militants - 21-year-old Reyaad Khan from Cardiff - represented a "clear and present danger".
Khan - who featured prominently in an IS recruiting video posted online - was said to be planning to attack commemorative events in the UK.
A second British fighter, Ruhul Amin, was also killed in the strike alongside another IS fighter. A third Briton, Junaid Hussain, who was said to be plotting with Khan, was killed three days later by a US drone.
Setting out the ISC's work programme, Mr Grieve said an "immediate priority" would be "the intelligence basis surrounding the recent drone strike in which British nationals were killed".