Iraqi security forces foiled an attack Sunday by Islamic State (IS) militants against the city of Tikrit, killing five IS militants, a provincial security source said.

The attacks occurred at dawn as dozens of IS militants attacked from the west of the city, 170 km north of of Baghdad, sparking heavy clashes with security forces and allied militias, or "Hashd Shaabi," the source told Xinhua on condition of anonymity.

The troops backed by helicopter gunships repelled the attack which attempted to gain a foothold in the city, the source said, adding that militants withdrew to the western desert of Tikrit following several hours of intense clashes.

"Five IS militants were killed and four of their vehicles were damaged, with seven security members injured," the source said.

The attack on Tikrit occurred as security forces and allied militias, backed by Iraqi and U.S.-led coalition aircraft, were fighting with extremist militants in the battleground town of Baiji, 40 km north of Tikrit.

However, for over a month the two sides have been involved in fierce tug-of-war battles inside and near the town.

Heavy clashes also continue near Baiji where Iraq's largest oil refinery is located, as security forces fight to drive out IS militants from the Baiji refinery, which militants seized large parts of.

The security situation in Iraq has drastically deteriorated since June 10 last year, when bloody clashes broke out between Iraqi security forces and the IS.

Source: XINHUA