BAGHDAD, Sept. 9 (Xinhua) -- A total of nine Islamic State (IS) militants were killed and four others captured on Monday in an operation by security forces and an airstrike by the U.S.-led coalition aircraft in the central Iraqi province of Salahudin.

After a reconnaissance operation in on the rugged area of Mteibijah near the provincial border with Diyala, a commando force from the Counter-Terrorism Service (CTS) conducted an airdrop operation on IS positions in the area, Mohammed al-Bazi from Salahudin's provincial police told Xinhua.

The CTS troops, backed by international coalition aircraft, clashed with the extremist militants, killing six of them and capturing four others, al-Bazi said.

Iraqi security forces repeatedly carried out operations to take control of Mteibijah area from IS militants, but the vast rugged land and nearby Himreen mountainous area have made it difficult for them to completely clear the area from the extremist militants.

Also in the province, the coalition aircraft acted on intelligence reports and carried out an airstrike on an IS hideout in Makhoul Mountain range, about 60 km north of the provincial capital Tikrit, destroying the hideout and killing a group leader and two militants inside, al-Bazi said.

The security situation in Iraq was dramatically improved after Iraqi security forces fully defeated the extremist IS militants across the country late in 2017.

IS remnants, however, have since melted in urban areas or resorted to deserts and rugged areas as safe havens, carrying out frequent hit-and-run attacks against security forces and civilians.