FILE PHOTO: A fighter of the Islamic State of Iraq and the Levant (ISIL) holds an ISIL flag and a weapon on a street in the city of Mosul, June 23, 2014. REUTERS/Stringer

ERBIL, Iraq (Reuters) - Islamic State militants have developed an improvised explosive device (IED) that can be launched from rifles or dropped from an aerial drone, an arms monitoring group said on Wednesday.

Conflict Armament Research (CAR) said the Sunni militant group was “promoting the development of ‘own-brand’ weapons” to provide its insurgents with otherwise unavailable armaments.

“The (IED) can be thrown, launched from an improvised rifle attachment, or in its most recent phases of development, dropped from a commercial, off-the-shelf unmanned aerial vehicle (UAV) or drone,” CAR said in a report following visits to Mosul in November, February and March.

Iraqi military and elite counter-terrorism forces launched a sweeping, U.S.-backed offensive in October to retake the city, Islamic State’s last major urban stronghold in Iraq seized in a lightning offensive in 2014.

They have retaken most of Mosul, including its half east of the Tigris River, and surrounded the militants in its northwest quarter including the Old City, home to the Grand al-Nuri mosque where IS declared a “caliphate” over parts of Iraq and Syria.

CAR, which identifies and tracks arms and ammunition in war zones, reported in December that IS had been making weapons on a scale and sophistication matching national military forces and that it had standardized production across its realm.

The monitor’s findings suggested IS was centrally managing the design and production of improvised weapons with the ability to test its systems on the field and refine them as well as use new technologies such as drones.

The report said Islamic State was using the battle for Mosul to field-test different types of ordnance, an important step in any weapons research and development program.

“Evidence of research and development by IS forces, compiled by CAR since 2014, suggests that such adaptations are likely to continue and will result in further UAV innovations in the near future, potentially for use in theaters other than Iraq.”