BAGHDAD: Iraqi forces have withdrawn from the militant-held city of Tikrit after their new offensive met heavy resistance, in a blow to the government effort to push back the insurgents controlling large parts of the country.

The failure highlights the difficulties of Baghdad’s struggle to recapture territory from the insurgents who seized Mosul, Tikrit and other cities last month in a rapid offensive which threatens to fragment Iraq on ethnic and sectarian lines.

The setback came as Iraqi politicians named a moderate Sunni as speaker of Parliament on Tuesday. That was a long-delayed first step toward a power-sharing government urgently needed to confront the militants, who are led by the Al-Qaeda offshoot Islamic State.

It is unclear if the election of Salim Al-Jabouri as speaker will break the broader deadlock over Prime Minister Nuri Al-Maliki’s bid to serve a third term. He has ruled since the April election as a caretaker.

Government troops and allied Shiite volunteer fighters retreated from Tikrit before sunset on Tuesday to a base four km south after coming under heavy mortar and sniper fire, a soldier who fought in the battle said. Residents said there was no fighting on Wednesday morning in Tikrit.

It is a stronghold of ex-army officers and loyalists of Saddam Hussein’s Baath Party who allied themselves with the Islamic State-led offensive last month.

Tuesday’s military attack was launched from Awja, Saddam’s birthplace some 8 km south of the city, but ran into heavy opposition in the southern part of the city.

Pictures published on Twitter by supporters of the Islamic State showed a fighter holding a black flag next to a black armored car it said had been abandoned by a military SWAT team, as well as vehicles painted in desert camouflage — one of them burnt out — which it said retreating troops left behind.