BAGHDAD, Dec. 31 (Xinhua) -- Thirteen Islamic State (IS) militants were killed Sunday in clashes with paramilitary Hashd Shaabi fighters in Iraq's eastern province e of Diyala, a Hashd Shaabi statement said.

The clashes took place when IS gunmen attacked the Hashd Shaabi posts at villages in north of the town of Maqdadiyah, some 100 km northeast of the Iraqi capital Baghdad, the statement said.

Later on, the Hashd Shaabi fighters carried out search operation looking for the attackers who withdrew to rural areas outside the villages, it said.

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.

Dozens of IS militants fled their former bases in Salahudin province and Hawijah area in west of Kirkuk after the Iraqi forces cleared these areas from the extremist militants during anti-IS offensives in the past few months.

On December 9, Iraqi Prime Minister Haider al-Abadi officially declared full liberation of Iraq from IS militants after Iraqi forces recaptured all the areas once seized by the extremist group.

However, small groups of IS militants resorted to deserts and rugged areas looking for safe havens but the security forces are hunting them down from time to time.