BAGHDAD, July 29 (Xinhua) -- Nine Islamic State (IS) militants were killed Sunday during an operation in a mountainous area in Iraq's eastern province of Diyala, a provincial security source said.

A joint force from Iraqi army, police and paramilitary Hashd Shaabi fighters, backed by helicopter gunships, launched an operation to clear IS militants in Diyala's part of Himreen mountainous area, Hassan Mohammed, deputy commander of Diyala Operation Command, told Xinhua.

The operation resulted in the killing of nine IS militants, including one wearing explosive belt, along with destroying a booby-trapped car and motorcycle, Mohammed said.

An army officer and three soldiers were also wounded during the operation, Mohammed added.

Despite repeated military operations in Diyala province, remnants of IS militants were still hiding in rugged areas near the border with Iran, as well as the sprawling areas extending from western part of Diyala to Himreen mountainous area in the northern part of the province.

Earlier in the day, four IS militants were reportedly killed and a fifth captured in a preemptive operation against an IS hideout in a desert area in west of the city of Samarra, some 120 km north of the Iraqi capital Baghdad, according to a statement by Yahya Rasoul, spokesperson for the Iraqi Joint Operations Command.

On Dec. 9, 2017, Iraqi Prime Minister Haider al-Abadi officially declared full liberation of Iraq from the IS. However, small groups of IS militants have since regrouped in rugged areas, carrying out attacks against security forces and civilians from time to time.