Iraqi police say Islamic State militants have blown up a strategic highway bridge north of Tikrit, as Iraqi soldiers and Shi'ite militiamen fight their way into the city.
The bridge is one of the few road links across the Tigris river and its demolition ruptured oil pipelines connecting Iraq's largest refinery, at Baiji, to an export pipeline in Kurdish territory.
Tikrit lies about halfway between the capital Baghdad and the country's second-larget city, Mosul, which is held by Islamic State militants.
Iraqi troops and allied Shi'ite militiamen entered Tikrit for the first time March 11 from the north and south.
Iraqi Defense Minister Khaled al-Obeidi on March 12 met with senior military commanders of the Tikrit operation as well as with Iranian General Qassem Soleimani, commander of the Quds Force, an elite unit of Iran's Revolutionary Guard.
Iran is helping coordinate the 30,000 troops and militiamen involved in the operation, which is not being supported by U.S.-led coalition air strikes.
Based on reporting by AP, dpa, and BBC
