BAGHDAD: Iraqi forces pressed Saturday their biggest offensive in months to resume their long-stalled northward advance and disrupt militants lines, security officers said.
After recapturing parts of Baiji and the huge nearby refinery complex from the ISIS group, security and allied paramilitary forces thrust further northward up the main highway leading to Mosul.
They reached the town of Zawiyah and vowed to push on to Sharqat, the northernmost town in Salaheddin province before the border with Nineveh province, of which Mosul is the capital.
"Iraqi forces are besieging the villages of Msahaq and Zawiyah," about 25 kilometers (16 miles) north of Baiji, a senior officer in Salaheddin operations command said.
Reclaiming control of that stretch of road and the villages along it would contribute to isolating ISIS strongholds east of the Tigris, such as Hawijah, from the self-proclaimed caliphate's heartland on the other side of the river.
"Retaking Zawiyah would divide the battlefield; Daesh will be in an awkward position," retired general and security analyst Abdel Karim Khalaf said, using an Arabic acronym for ISIS.
"Their transport towards Tikrit and Ramadi will be complicated, the secondary itineraries are long and difficult," he said.
Iraqi forces, including thousands of fighters from the Popular Mobilization organisation dominated by Tehran-backed Shiite militias, were still battling ISIS in and around Baiji Saturday.
They were also securing Sinniya, a nearby town which commands access to the road leading to the western Anbar province, where thousands more forces were closing in on the capital Ramadi.
Further west along the Euphrates, Iraqi troops backed by Sunni tribal fighters and U.S.-led coalition strikes were fighting to retake the town of Baghdadi.
Iraqi forces' recaptured the ISIS stronghold of Tikrit, 160 kilometers (100 miles) north of Baghdad in April.
The government then lost its last foothold in Ramadi, west of Baghdad, in mid-May.
Anti-ISIS operations, slowed by searing summer temperatures, had since focused mainly on training and disrupting ISIS supply lines rather than territorial reconquest.
Mosul, Iraq's second city and the ISIS group's largest hub, is around 125 kilometers north of Zawiyah.
As Iraqi forces marched past Baiji, there were several reports of residents fleeing their ISIS-held villages to meet the pro-government forces or turning against the militants.
Residents of Sharqat, north of Zawiyah, told AFP that a man who had two relatives executed by ISIS since the militants took over his town last year, opened fire on ISIS members and killed five before being shot dead himself.
Hundreds of fighters from Sunni tribes opposed to ISIS are involved in the Salaheddin operation.