|A member of the Iraqi Army carries anti missiles during clashes with Islamic State militants at the south of Mosul, Iraq December 12, 2016. REUTERS/Ammar Awad
The extra forces are being deployed as the grueling U.S.-backed campaign to crush Islamic State in its Iraqi stronghold enters its ninth week. Elite army troops have retaken a quarter of the city, but their advance has been slow and punishing.
The federal police units, around 4,000 strong, have been moved to an area southeast of the city, near where an army tank division last week made the deepest incursion into Mosul so far, briefly seizing a hospital used as a base by the militants.
The troops were forced to pull back from the Salam hospital, less than a mile (about 1 km) from the Tigris river which runs through the center of Mosul, when they were attacked by suicide car bombs, mortar volleys and machine gun fire.
A spokesman for Iraq's federal police commander, Lieutenant-General Raed Shakir Jawdat, said the police units were near Qaraqosh, about 15 km (10 miles) from the southeast edge of Mosul, and were ready to mobilize.
However, he said they were waiting for advances elsewhere on the eastern front, where elite Counter Terrorism Services (CTS) have made steady street-by-street progress, unlike last week's dramatic push by the armored division towards the hospital.
"We are waiting for orders from the supreme commanders to start the offensive to defeat Daesh (Islamic State) and clear the eastern part (of Mosul)," he said.
The CTS forces said on December 11 they had captured another district of east Mosul, al-Nour neighborhood.
Accounts from Mosul are difficult to confirm since authorities have increasingly restricted international media access to the battlefronts and areas retaken from Islamic State in and around the city.
Prime Minister Haider al-Abadi tried to play down concerns over the slow pace of progress, saying the recapture of cities such as Ramadi and Baiji from Islamic State had taken four times longer than the Mosul campaign so far.
Visiting commanders near Mosul on December 12, a day after a trip by U.S. Defense Secretary Ash Carter, Abadi also said the United States and other allies must continue to support Iraq's battle against what he said was a global threat posed by the militants.
Defeating Islamic State "requires cooperation with all countries... and this is why we appeal to the new U.S. presidency to take this into consideration," Abadi said.
The prime minister, who spoke to Donald Trump last month, said the president-elect promised "not just to continue American support but to increase it".
Carter told reporters on December 11 the battle for Mosul "hasn't been an easy fight (and) won't be an easy fight", but said it was going to plan.
He was speaking to reporters after meeting U.S. Lieutenant-General Steve Townsend, commander of the U.S.-led coalition supporting Iraqi forces in Mosul, who said that more than 2,000 Islamic State fighters had been killed or badly wounded.