TIKRIT, Iraq, Feb. 10 (Xinhua) -- Three government-backed Sunni tribal fighters were killed Saturday and two others wounded in attack by Islamic State (IS) militants in east of Tikrit, the capital of Salahudin province, a paramilitary tribal leader said.

The attack occurred at dawn when IS militants attacked an outpost of the tribal fighters in Jillam Albu-Ajil area in east of Tikrit, which located some 170 km north of the Iraqi capital Baghdad, Sheikh Ali Mohammed al-Ajili, the leader of the paramilitary tribal group, told Xinhua.

The IS militants came from the rugged area of Mteibijah, which has long been a redoubt of IS militants despite repeated anti-IS military operations in the sprawling rugged areas in the eastern part of Salahudin province and extend to the neighboring Diyala province and the nearby Himreen mountainous area.

During the past few months, dozens of IS militants fled their former bases in the predominately Sunni Arab province of Salahudin, Hawijah area in west of Kirkuk, after the Iraqi forces drove out the extremist militants from these areas during anti-IS offensives in the past few months.

On Dec. 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 and individuals of IS militants melted in urban areas or resorted to deserts and rugged areas looking for safe havens. They still capable of carrying out attacks from time to time against the security forces and civilians.