BAGHDAD, Sept. 9 (Xinhua) -- The death toll of the extremist Islamic State (IS) militants in an airdrop operation on IS positions in Iraq's central province of Salahudin on Monday rose to 15, the Iraqi military said.

The Counter-Terrorism Service (CTS), backed by international coalition aircraft, conducted an airdrop operation on IS positions in the rugged area of Mteibijah near the provincial border with neighboring Diyala province, Yahya Rasoul, spokesman of the Iraqi Joint Operations Command, said in a statement.

The troops killed 15 IS militants and captured nine others, along with destroying several hideouts, tunnels and training camp for the extremist militants, Rasoul said.

Earlier in the day, Mohammed al-Bazi from Salahudin's provincial police told Xinhua that the CTS airdrop operation killed six IS militants and captured four others.

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 of the extremist militants.

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.