Several thousand Iraqi federal police are ready to join the assault against Islamic State in east Mosul and the forces are being deployed as the gruelling U.S.-backed campaign to crush Islamic State in its Iraqi stronghold.They have already retaken a quarter of the city, but their advance has been slow and punishing. “We are waiting for orders from the supreme commanders to start the offensive to defeat ISIS and take the eastern part (of Mosul),” have said the source. The fight in crowded residential areas has also restricted the use of heavy weapons and air strikes from the U.S.-led coalition. 4.000 federal police units have been moved to southeast of the city, near an area where an army tank division last week made the deepest incursion into Mosul so far, taking a hospital used as a base by the militants. The troops were forced to pull back from the hospital, about 1 km from the Tigris river which runs through the centre of Mosul, when they were attacked by suicide car bombs, mortar volleys and machine gun fire.