US President Donald Trump has revoked a policy that required the Central Intelligence Agency to account for civilian deaths from drone strikes.

The move reversed a two-year-old order by his predecessor Barack Obama, who came under pressure for greater transparency after sharply increasing the use of drones for targeted attacks in military and counter terrorism operations.

It could give the CIA greater latitude to conduct strikes as Mr Trump increasingly relies on the spy agency, rather than the military, for lethal drone operations.

Mr Trump's action rescinded the 2016 order by Mr Obama requiring the US director of national intelligence to report annually the number of strikes taken against "terrorist targets" outside of active war zones, and give an assessment of combatant and civilian deaths that resulted.

Mr Trump's move though applied only to strikes by non-defence department agencies - the CIA, in effect.

It did not overturn requirements set by Congress for the Pentagon to account for civilian casualties in its operations.

US Air Force personnel prepare to launch a Predator drone from a base in the Persian Gulf

Activists say the move could make the CIA even less accountable than in the past.

Rights groups immediately criticised the move, saying it reverses a hard-fought effort for transparency and accountability in drone strikes, which became central to US strategy in the wake of the 11 September, 2001 Al-Qaeda terror attacks on the United States.

"The Trump Administration's action is an unnecessary and dangerous step backwards on transparency and accountability for the use of lethal force, and the civilian casualties they cause," said Rita Siemion of Human Rights First.