(Recasts with Ramadi fighting)
BAGHDAD, Jan 19 (Reuters) - Iraqi tribesmen backed by police special forces and helicopter gunships assaulted al Qaeda-linked militants in the eastern and southern outskirts of the city of Ramadi on Sunday, police and local officials said.
They said the ground forces retook a police station in al-Hamthiya on the eastern outskirts of the city after helicopters fired missiles and machineguns at militant hideouts in the area.
The fighting around Ramadi, the capital of the western Sunni province of Anbar, was some of the heaviest in several days.
The Islamic State in Iraq and the Levant (ISIL), an al Qaeda offshoot also fighting in Syria, and its local allies overran parts of Ramadi, as well as the nearby city of Falluja, on Jan. 1 after security forces broke up a Sunni protest camp near Ramadi and arrested an outspoken Sunni lawmaker.
The security forces and Sunni tribesmen opposed to al Qaeda had regained control of most of Ramadi earlier this month, but militants retained footholds on the edges of the city.
The authorities imposed an indefinite curfew in Ramadi, 100 km (60 miles) west of Baghdad, on Sunday to try to avert civilian casualties, police said.
Army units have deployed around Falluja, but Prime Minister Nuri al-Maliki has ruled out an all-out assault for now, saying the city's tribes must evict al Qaeda militants themselves.
Earlier in the day, gunmen wearing army uniforms killed at least six government-backed Sunni militiamen at a checkpoint near Baquba, 65 km (40 miles) northeast of Baghdad, police said.
They said the victims included the local leader of the "Sahwa" (Awakening) tribal militia, along with two of his sons.
Sahwa fighters, who helped U.S. troops turn the tide against al Qaeda-linked militants in Iraq from 2006 onwards, are often targeted by insurgents battling the Shi'ite-led government.
Two years after U.S. troops left Iraq, violence has climbed back to its highest levels since the Sunni-Shi'ite bloodletting of 2006-2007, when tens of thousands of people were killed.
The United Nations says nearly 9,000 people died violently in Iraq last year, all but 1,050 of them civilians.
The toll from violence on Saturday rose to at least 32 killed, including six men involved in an attack on a juvenile prison in Baghdad, and 75 wounded, police and medics said. (Reporting by Ahmed Rasheed; Writing by Alistair Lyon; Editing by Sophie Hares)