BAGHDAD, June 20 (Xinhua) -- Iraqi security forces on Friday continued fierce clashes with Sunni militant groups in several Iraqi provinces, while the troops repelled attacks on major oil refinery in Salahudin province, security sources said.
The security forces, with air support, fought back a major attack by militants against the oil refinery of Baiji, located some 200 km north of the capital Baghdad, a security source from Salahudin province told Xinhua on condition of anonymity.
Sunni militants, including those who are linked to the Islamic State in Iraq and Levant (ISIL), an al-Qaida offshoot, have carried out several attacks to take control of Iraq largest of Baiji, but were repelled repeatedly by the security forces.
Earlier, insurgent groups overran the city of Baiji as well as large parts of the Sunni-predominant province of Salahudin, including its capital Tikrit, some 170 km north of Baghdad.
In Iraq's northern province of Nineveh, security forces backed by volunteers continued fighting militant groups in the city of Tal Afar, some 70 km west of the provincial capital Mosul, and retook control of some neighborhoods, leaving at least 15 militants killed, a provincial police source told Xinhua.
Fierce battle in Tal Afar airport, just outside the city, are still underway, the source said.
Tal Afar is the largest city in the Sunni-majority province of Nineveh after the provincial capital Mosul, some 400 km north of Baghdad, and is also the last foothold of the Iraqi Shiite-led government in Nineveh province, except for the parts that are under the Kurdish security forces.
Tal Afar is also a mixed city of mainly Shiite and Sunni Turkomans, in addition to the Kurds and other ethnic and religious minorities.
The battles in Tal Afar pushed most of its 250,000 population to flee their homes, mainly to the semi-autonomous region of Kurdistan and the city of Sinjar, some 60 km west of Tal Afar.
The Sunni-majority province of Nineveh and its capital Mosul have long been a stronghold for insurgent groups, including al- Qaida militants, since the U.S.-led invasion of Iraq in 2003.
In Anbar province, insurgent groups took control of a border crossing point with Syria near the city of al-Qaim, some 330 km northwest of Baghdad, and seized several border posts after clashes with the security forces, leaving 22 soldiers killed, a provincial police source said.
Later in the day, the troops backed by allied tribesmen have clashed with militant groups who tried to take control of the city of al-Qaim, but the attackers failed to enter the city, the source said.
In the country's eastern province of Diyala, a joint force from soldiers, policemen and Shiite militiamen raided an insurgent position on the edges of the city of Udheim, some 60 km north of the provincial capital city of Baquba, Major General Jamil al- Shimary, provincial police chief, told Xinhua. The joint force managed to kill the local ISIL leader in the city and several of his aides after a fierce clash on the site, al- Shimary said.
Diyala province, which stretches from eastern edges of Baghdad to the borders with Iran, has long been the stronghold of al-Qaida militant groups as well as a hotbed of insurgency and sectarian violence since the U.S.-led invasion in 2003.
Iraq has seen a deteriorating security situation since June 10 when bloody clashes broke out between security forces and hundreds of Sunni militants who took control of Mosul and later seized swathes of territories after the Iraqi security forces withdrew from their posts in Nineveh and other predominantly Sunni provinces.