BAGHDAD, Feb. 5 (Xinhua) -- Iraqi security forces Monday killed six Islamic State (IS) militants in an operation at the town of Hawijah in Iraq's northern province of Kirkuk, a local police source said.

The incident took place in the morning when a federal police forces carried out a search operation to clear the central part of Hawijah, some 230 km north of the Iraqi capital Baghdad, from possible remnants of IS militants, Captain Ahmed al-Jubouri told Xinhua.

During the operation, the troops came under small arms fire from some houses in the town sparking heavy clash that resulted in the killing of six militants, Jubouri said without giving further details.

The operation was aimed at clearing the central neighborhoods of the town to pave the way for the displaced residents to return to their homes, Jubouri added.

Dozens of IS militants fled their former bases in Hawijah area in west of Kirkuk and the neighboring Salahudin province after the Iraqi forces drove out the extremist militants from these areas 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 and individuals of IS militants melted in urban areas or resorted to deserts and rugged areas looking for safe havens but the security forces are hunting them down from time to time.